Pydantic bump, fix readthedocs w/ Poetry 1.8

[harrisonliew]

• Poetry 1.8 broke readthedocs - implemented the temporary fix.
• Also bumped to pydantic v2 (with requisite migration).
• Added tests/ to mypy type checking.
• Dev documentation updates.

Related PRs / Issues

Type of change:

• Bug fix
• New feature
• Other enhancement

Impact:

• Change to core Hammer
• Change to a Hammer plugin
• Other

Contributor Checklist:

• Did you set master as the base branch?
• Did you state the type-of-change/impact?
• Did you delete any extraneous prints/debugging code?
• (If applicable) Did you add documentation for the feature?
• (If applicable) Did you update the poetry.lock file if you updated the requirements in pyproject.toml?
• (If applicable) Did you add a unit test demonstrating the PR?
• (If applicable) Did you run this through the e2e integration tests?
• (If applicable) Did you update the submodules in e2e/ if this feature depends on updated plugins?

[vighneshiyer]

Thanks! There are a few pydantic APIs to update in tests which the bump-pydantic script doesn't seem to touch, not sure why that's not working, but we can fix these by hand.

Also, now may be a good time to add mypy -p tests to workflows/pr.yml. There have been failing typechecks for tests that we can patch in this PR too.

[vighneshiyer]

Everything looks good