Add MyPy github action

[RCoder01]

Add an action that automatically runs mypy on every commit

It should run on every mrobosub_[package], but currently mrobosub_planning is the only package that has no type issues, so we should only block merges if type checking fails there. This can be expanded to more packages as we improve the codebase.

• [x] MyPy is running on every commit
• [ ] Mypy is required to pass (in mrobosub_planning) in order to merge to devel or main

[RCoder01]

Finished, thanks @BhavyeMathur!