Fix some type errors found with pyright

[jacobtomlinson]

Exploring adding pyright and fixing up type errors. Perhaps this should replace mypy? Or be used alongside?

This PR started out as an exploration of adding pyright to our standard linting tooling, but ultimately ended up just fixing some type errors found by pyright as a one off. See #448 (comment) for info on why it wasn't added to pre-commit.

xref #428 #381

[codecov]

Codecov Report

Attention: Patch coverage is 88.23529% with 6 lines in your changes missing coverage. Please review.

Project coverage is 95.03%. Comparing base (87063fc) to head (e1adb0b).
Report is 123 commits behind head on main.

Files with missing lines	Patch %	Lines
kr8s/_objects.py	81.81%	4 Missing ⚠️
kr8s/_api.py	80.00%	1 Missing ⚠️
kr8s/_types.py	85.71%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #448      +/-   ##
==========================================
+ Coverage   94.61%   95.03%   +0.41%     
==========================================
  Files          29       30       +1     
  Lines        3141     3867     +726     
==========================================
+ Hits         2972     3675     +703     
- Misses        169      192      +23     

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[jacobtomlinson]

It looks like pyright doesn't currently work in pre-commit CI RobertCraigie/pyright-python#164.

There also seem to be some challenges with how pyright is packaged as it depends on a node package which gets installed at runtime, which seems a bit flaky.

Lastly, there seems to be some controversy between pyright and a fork called basedpyright. Seeing discussions like microsoft/pyright#8065 makes me apprehensive to use either project until some of the discussions reach a resolution.

Given all of this I think we should hold off adding full pyright linting here and just stick with mypy. But I'm still keen to merge the typing improvements that were made in this PR.