[back] feat(notifications): u#2900 notify when the status of a story has changed

[bameda]

This PR notifies assigned users and its creator when the story changes its status.

This can happen:

• In kanban, when a story changes to another column.
• From the detail panel of a story, through the status selector.
• When a state is deleted and its stories are requested to move to another

How to validate:

• Review the code
• Roses are red and tests are green
• Manual test. Notifications must be created when some user...
  • Move stories in the kanban
  • Change status in the story's detail panel
  • Remove status moving stories to another status

[github-actions]

Coverage Report

File	Stmts	Miss	Cover	Missing
src/taiga
__main__.py	71	71	0%	17–155
src/taiga/attachments
admin.py	27	3	90%	25, 28, 70
events.py	8	2	75%	15, 20
models.py	19	2	89%	61, 64
repositories.py	49	1	97%	62
src/taiga/auth/services
__init__.py	47	0	98%	90–>93
src/taiga/base
mocks.py	74	12	80%	93–94, 107–118, 143–>exit
src/taiga/base/api
permissions.py	49	1	99%	22
requests.py	11	3	80%	15, 21–23
src/taiga/base/db
__init__.py	4	1	75%	15
commands.py	52	52	0%	8–269
sequences.py	45	2	97%	91–92
src/taiga/base/db/admin
forms.py	14	8	38%	17–25
utils.py	11	7	36%	17–23
src/taiga/base/db/models
fields.py	15	1	88%	20
src/taiga/base/django
__init__.py	5	2	60%	17–19
settings.py	30	2	93%	16–17
urls.py	3	3	0%	8–11
src/taiga/base/i18n
__init__.py	102	9	88%	171–>170, 173–>170, 192–193, 203–205, 215, 268, 279, 283
choices.py	34	2	91%	80, 87
commands.py	74	74	0%	8–108
src/taiga/base/logging
formatters.py	24	10	50%	22–>exit, 38, 44–45, 51–60
middlewares.py	23	1	96%	20
src/taiga/base/repositories
neighbors.py	39	3	91%	43–44, 65
src/taiga/base/sampledata
commands.py	11	11	0%	8–40
constants.py	15	15	0%	14–51
demo_data.py	273	273	0%	8–529
factories.py	122	122	0%	9–353
test_data.py	290	290	0%	8–634
src/taiga/base/serializers
fields.py	34	3	93%	22, 47, 61
src/taiga/base/utils
commands.py	11	11	0%	8–30
datetime.py	44	18	60%	54, 67, 126–147
enum.py	14	1	92%	43
images.py	26	3	87%	21–22, 30
json.py	33	15	45%	30–35, 37, 39–44, 46, 50
pprint.py	6	6	0%	8–17
slug.py	23	4	85%	22–25
src/taiga/base/validators/fields
i18n.py	15	1	95%	19
uuid.py	14	1	95%	19
src/taiga/comments
admin.py	29	3	92%	16, 20, 24
events.py	11	3	73%	15, 20, 25
models.py	20	2	91%	43, 46
src/taiga/commons/storage
commands.py	13	13	0%	8–40
models.py	16	2	88%	38, 41
services.py	9	0	92%	17–>16
tasks.py	9	9	0%	8–19
src/taiga/conf
__init__.py	94	3	95%	112, 128–129
tokens.py	17	1	90%	34
src/taiga/emails
commands.py	35	35	0%	9–68
sender.py	18	5	71%	48–50, 54–73
tasks.py	39	4	90%	44–45, 53–54
src/taiga/events
app.py	18	1	92%	21
events.py	16	2	88%	31–32
logging.py	39	23	31%	18–>exit, 32–48, 51–60
manager.py	117	11	90%	78–79, 223–233, 239–242
responses.py	33	6	84%	33, 37–41
subscriber.py	80	4	95%	51, 55, 88, 91, 108–>120
src/taiga/events/actions
auth.py	23	11	44%	27–32, 39–45
event_handlers.py	9	4	56%	18–20, 28–30
projects.py	55	30	38%	36–40, 48–64, 72–80, 88–96
workspaces.py	55	30	38%	36–40, 48–64, 72–80, 88–96
src/taiga/events/pubsub/backends
base.py	30	1	98%	53
redis.py	66	5	94%	41–43, 85–86
src/taiga/exceptions/api
__init__.py	27	0	97%	28–>30
handlers.py	27	2	90%	27–28
middlewares.py	26	2	87%	37, 41
src/taiga/integrations/auth
services.py	39	7	82%	50–56
src/taiga/integrations/github
services.py	40	0	98%	63–>68
src/taiga/mediafiles
admin.py	20	2	91%	24, 27
models.py	26	2	92%	84, 87
src/taiga/notifications
admin.py	11	2	85%	20, 23
repositories.py	26	1	94%	77
src/taiga/permissions
services.py	103	1	98%	28, 106–>109
src/taiga/permissions/validators
fields.py	24	3	88%	18–19, 45
src/taiga/projects/invitations
models.py	25	2	92%	89, 92
repositories.py	84	1	98%	135
src/taiga/projects/invitations/api
validators.py	65	7	89%	38–40, 65–66, 84–85
src/taiga/projects/invitations/events
__init__.py	33	1	91%	37–>exit, 49–>exit, 74–>exit, 102
src/taiga/projects/invitations/services
__init__.py	183	1	99%	58–>53, 286
src/taiga/projects/memberships
models.py	16	2	88%	51, 54
repositories.py	86	2	97%	91, 124
src/taiga/projects/memberships/events
__init__.py	16	2	88%	18–24
src/taiga/projects/memberships/services
__init__.py	45	1	95%	64–>69, 111
src/taiga/projects/projects
admin.py	53	12	75%	33–34, 39–42, 50–51, 56–59, 90, 94
models.py	61	8	86%	64, 67, 78, 113, 116, 119–121
repositories.py	115	4	96%	125, 126–>129, 155, 254–255
tasks.py	6	1	88%	17
src/taiga/projects/projects/services
__init__.py	107	5	92%	78, 87, 199, 205–>208, 213, 235
src/taiga/projects/references
mixins.py	13	0	93%	25–>28
src/taiga/projects/roles
api.py	35	3	93%	46–48
models.py	26	3	86%	50, 53, 57
repositories.py	44	1	96%	92
src/taiga/projects/roles/services
__init__.py	25	1	94%	24, 57–>62
src/taiga/stories/assignments
models.py	15	2	87%	42, 45
repositories.py	52	1	97%	49
src/taiga/stories/assignments/notifications
__init__.py	18	0	91%	25–>27, 44–>46
src/taiga/stories/attachments
api.py	51	1	97%	159
serializers.py	11	0	93%	20–>28
src/taiga/stories/comments
api.py	58	1	97%	177
src/taiga/stories/stories
admin.py	25	5	84%	76–81, 85, 89
models.py	25	2	92%	73, 76
src/taiga/stories/stories/notifications
__init__.py	11	0	93%	21–>23
src/taiga/stories/stories/services
__init__.py	142	2	98%	232–>249, 293, 317
src/taiga/tasksqueue
app.py	20	2	86%	29–30
commands.py	65	65	0%	8–122
logging.py	33	17	40%	18–>exit, 29–39, 42–51
manager.py	56	13	77%	37, 41, 45, 49, 94, 163, 177, 186, 191, 198, 202, 209, 213
task.py	12	1	92%	23
src/taiga/tokens
admin.py	44	10	81%	67, 70, 73, 76, 104, 108, 112, 116, 120, 124
models.py	30	4	87%	59, 62, 78, 81
src/taiga/users
admin.py	51	7	81%	32, 41, 50, 87–95
commands.py	9	9	0%	8–26
models.py	65	10	86%	71, 74, 90, 93, 97, 100, 103, 106, 127, 130
repositories.py	204	3	98%	209–>212, 335, 428–429
src/taiga/users/api
__init__.py	66	2	96%	216, 304
src/taiga/users/api/validators
__init__.py	42	3	92%	39–41
src/taiga/users/services
__init__.py	244	7	95%	75, 259, 262–>257, 297–>280, 306–>280, 322–>318, 345–>341, 366, 494–>499, 513–520, 521–>526, 524–525
src/taiga/workflows
models.py	40	4	90%	42, 45, 85, 88
src/taiga/workflows/services
__init__.py	114	4	94%	54, 233, 260, 334–>343, 350
src/taiga/workspaces/invitations
models.py	24	2	92%	84, 87
permissions.py	9	1	82%	19
repositories.py	77	1	98%	123
src/taiga/workspaces/invitations/api
validators.py	18	2	88%	24–25
src/taiga/workspaces/invitations/events
__init__.py	25	1	91%	36–>exit, 60–>exit, 71
src/taiga/workspaces/invitations/services
__init__.py	123	1	99%	222
src/taiga/workspaces/memberships
api.py	43	1	96%	126
models.py	15	2	87%	43, 46
repositories.py	63	2	95%	72, 105
src/taiga/workspaces/memberships/services
__init__.py	46	1	97%	117
src/taiga/workspaces/workspaces
admin.py	57	19	62%	25–26, 31–34, 49, 52–57, 61, 65, 73–74, 79–82
models.py	18	2	90%	32, 35
repositories.py	127	2	99%	232–233
src/taiga/workspaces/workspaces/services
__init__.py	54	2	94%	113, 116
TOTAL	10104	1547	83%

Tests	Skipped	Failures	Errors	Time
1161	1 💤	0 ❌	0 🔥	23m 34s ⏱️