Address failing tests in repo-review

[ukmo-ccbunney]

PR #456 added repo-review as a pre-commit hook using the sp-repo-review plugin (https://pypi.org/project/sp-repo-review/)

Several of the checks are failing for the cf-units repository (expected). The failing tests are currently set in an ignore list in pyproject.toml to avoid failures in the workflow, but it would be good practice if we could address them:

Test

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1. PY005: Has tests folder
2. PP003: Does not list wheel as a build-dep
3. PP304: Sets the log level in pytest
4. PP305: Specifies xfail_strict
5. PP306: Specifies strict config
6. PP307: Specifies strict markers
7. PP309: Filter warnings specified
8. GH104: Use unique names for upload-artifact
9. GH212: Require GHA update grouping
10. PC110: Uses black or ruff-format
11. PC140: Uses a type checker
12. PC160: Uses a spell checker
13. PC170:Uses PyGrep hooks (only needed if rST present)
14. PC180:Uses a markdown formatter
15. PC190: Uses Ruff
16. PC901: Custom pre-commit CI message
17. MY100: Uses MyPy (pyproject config)
18. MY103: Warn unreachable
19. MY105: MyPy enables redundant-expr
20. RF001: Uses RUFF

We may decide some checks are not relevant, in which case they can be removed from this above TODO list and left in the ignore list in pyproject.toml

[ukmo-ccbunney]

Several tests resolved in #522