Improve mypy strictness

[l0b0]

Related Issue(s): #332

Description: Applies stricter mypy configuration to the code base

PR Checklist:

• Code is formatted (run scripts/format)
• Tests pass (run scripts/test)
• This PR maintains or improves overall codebase code coverage.
• Changes are added to the CHANGELOG. See the docs for information about adding to the changelog.

[codecov-commenter]

Codecov Report

Merging #394 (a1d50f0) into main (c2b7e0e) will decrease coverage by 0.06%.
The diff coverage is 89.85%.

@@            Coverage Diff             @@
##             main     #394      +/-   ##
==========================================
- Coverage   89.82%   89.75%   -0.07%     
==========================================
  Files          38       38              
  Lines        4953     4959       +6     
==========================================
+ Hits         4449     4451       +2     
- Misses        504      508       +4     

Impacted Files	Coverage Δ
pystac/serialization/__init__.py	86.95% <ø> (ø)
pystac/stac_io.py	71.73% <54.54%> (-0.65%)	⬇️
pystac/item.py	96.67% <86.66%> (-0.56%)	⬇️
pystac/__init__.py	97.14% <100.00%> (ø)
pystac/catalog.py	93.51% <100.00%> (ø)
pystac/collection.py	93.35% <100.00%> (ø)
pystac/extensions/base.py	89.36% <100.00%> (ø)
pystac/extensions/label.py	85.89% <100.00%> (ø)
pystac/extensions/pointcloud.py	96.61% <100.00%> (ø)
pystac/serialization/common_properties.py	94.64% <100.00%> (ø)
... and 5 more

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[lossyrob]

Noting here that the type ignores were to avoid showing errors for unused imports in VS Code with Pylance, with the reportUnusedClass flag set. This was set in my configuration but not a project-level configuration, where the default Pyright behavior is to ignore this.

The better solution is to ignore reportUnusedClass in the VS Code Pylance settings (which is the default) and to ensure flake8 is set as the linter for the project; that way unused imports that are not in init.py (which are ignored via the # flake8: noqa directive) will be caught in VS Code.

[l0b0]

Are we going to support three different type hint linters (mypy, pylance and pyright)? That sounds like a very difficult task, especially if one of them doesn't run in CI.

[duckontheweb]

@lossyrob My understanding of your comment is that those ignores were specific to your VS Code setup and that we are okay to drop them as @l0b0 has done here. It seems like this is mostly a PSA to other VS Code users on how to handle this. Is that right?

Might also be good to get your input on #381. My feeling is that we should settle on 1 type checker, but would be good to get other input.

[lossyrob]

Pylance is backed by Pyright, so they are the same thing.

I had given a thumbs up on #381. I'd like to avoid a situation where Pyright (and therefore VS Code) thinks there's an error that passes CI, as it's great to be able to detect errors during editing, I find that to be the most accelerating change in my workflow in years - reminds me of when I had static compilation feedback working with other languages. However, a single type checker makes sense, and as mypy is more strict I'm hoping we A. don't get into the situation where pyright breaks, and B. some useful type-level code is blocked by mypy. Seems like that's not happening yet; also I don't think this project needs to fit to any of our personal preferences or workflows, so I think going with mypy only is a good choice.

You are correct in that my comment here was just a note in way of explination of why the type:ignores were there in the first place, and a documentation of working out how to better set up VS Code for this project.