Fixed typing in 'import_classes_from_module' function

[gchqdev227]

This PR fixes a typing error that occurs in the import_classes_from_module function on newer versions of mypy:

concoursetools/importing.py:73: error: Incompatible return value type (got "dict[str, type[object]]", expected "dict[str, type[T]]")  [return-value]

For some reason, issubclass was not type narrowing. I've rewritten the code slightly to drop a conditional in favour of an earlier continue statement. This also avoids a tiny bit of work for other classes.

In additional, I dropped a try/except block for a TypeError raised by issubclass. I assume this exists because issubclass will raise TypeError if not passed a class, but given we're running inspect.isclass as a predicate above, I assume the only issue we could have here would be due to some particularly heinous metaprogramming, so I think it's fine!

This has now been reverted, as it turns out the issue was due to Python 3.10.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud