gh-37281: details in Zariski-Van-Kampen
Small changes in the modified files, about pep8 and ruff warnings about
code
### :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/37281
Reported by: Frédéric Chapoton
Reviewer(s): grhkm21, Martin Rubey
