Modernize type annotations and improve mypy config

[jwodder]

No description provided.

[codecov]

Codecov Report

Attention: 7 lines in your changes are missing coverage. Please review.

Comparison is base (9335182) 89.04% compared to head (f23cfff) 89.05%.
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1343   +/-   ##
=======================================
  Coverage   89.04%   89.05%           
=======================================
  Files          76       75    -1     
  Lines       10243    10284   +41     
=======================================
+ Hits         9121     9158   +37     
- Misses       1122     1126    +4     

Flag	Coverage Δ
unittests	89.05% <97.35%> (+<0.01%)	⬆️

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Files	Coverage Δ
dandi/cli/__init__.py	80.00% <100.00%> (ø)
dandi/cli/cmd_move.py	100.00% <ø> (ø)
dandi/cli/cmd_validate.py	78.78% <100.00%> (ø)
dandi/cli/tests/test_cmd_ls.py	100.00% <100.00%> (ø)
dandi/cli/tests/test_command.py	100.00% <100.00%> (ø)
dandi/cli/tests/test_download.py	88.70% <100.00%> (ø)
dandi/cli/tests/test_instances.py	100.00% <100.00%> (ø)
dandi/cli/tests/test_move.py	100.00% <100.00%> (ø)
dandi/cli/tests/test_service_scripts.py	98.24% <100.00%> (ø)
dandi/conftest.py	100.00% <100.00%> (ø)
... and 36 more

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[github-actions]

🚀 PR was released in 0.58.1 🚀