gh-37078: use parent in weyl_algebra.py
Using `Parent` instead of `Algebra`
also full pep8 cleanup of the modified file, plus some typing
annotations
### :memo: Checklist
- [x] The title is concise, informative, and self-explanatory.
- [x] The description explains in detail what this PR is about.
URL: https://github.com/sagemath/sage/pull/37078
Reported by: Frédéric Chapoton
Reviewer(s): Travis Scrimshaw
