Fix error in duplicate PREMIS event ID handling

[mcantelon]

Attempting to create a UUID object using an existing UUID object, rather than a string, results in an error. Changed duplicate PREMIS event identifier handling to avoid ending up doing this.

[replaceafill]

Thanks for catching and fixing this @mcantelon!

What do you think of updating the test module like this:

 def test_ensure_event_id_is_uuid(mocker, params):
     if params["message_logged"]:
-        mocker.patch("uuid.uuid4", return_value="f4eea76b-1921-4152-b1b4-a93dbbfeaaef")
+        mocker.patch(
+            "uuid.uuid4", return_value=uuid.UUID("f4eea76b-1921-4152-b1b4-a93dbbfeaaef")
+        )
     printfn = mocker.Mock()
     result = load_premis_events_from_xml.ensure_event_id_is_uuid(
         params["event_id"], printfn
     )
+    assert isinstance(result, str)
     if not params["message_logged"]:
         assert result == params["event_id"]
         printfn.assert_not_called()

This updates the test of that specific function test_ensure_event_id_is_uuid and fixes the wrong return value of the mock which should be a uuid.UUID type, not a string. Then it adds an assertion on result similar to yours but using isinstance which is recommended for this use case.

[mcantelon]

@replaceafill Nice! I've updated the PR!

[replaceafill]

Looks good @mcantelon, thank you!