Drop support for Python < 3.10 and add additional Ruff rules

[sciyoshi]

There were some tests that weren't being run at all due to a missing call. This PR also adds it and fixes some issues that were uncovered.

[codecov]

Codecov Report

Attention: Patch coverage is 71.63121% with 120 lines in your changes are missing coverage. Please review.

Project coverage is 82.74%. Comparing base (c708b2e) to head (5dbecf4).

Files	Patch %	Lines
prosemirror/model/from_dom.py	79.01%	17 Missing ⚠️
prosemirror/model/schema.py	66.66%	16 Missing ⚠️
prosemirror/model/node.py	55.55%	12 Missing ⚠️
prosemirror/model/replace.py	36.84%	12 Missing ⚠️
prosemirror/model/to_dom.py	37.50%	10 Missing ⚠️
prosemirror/transform/transform.py	56.52%	10 Missing ⚠️
prosemirror/transform/mark_step.py	66.66%	8 Missing ⚠️
prosemirror/model/fragment.py	77.77%	6 Missing ⚠️
prosemirror/model/resolvedpos.py	66.66%	6 Missing ⚠️
prosemirror/transform/step.py	45.45%	6 Missing ⚠️
... and 6 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #313      +/-   ##
==========================================
- Coverage   83.31%   82.74%   -0.58%     
==========================================
  Files          30       30              
  Lines        4136     4161      +25     
==========================================
- Hits         3446     3443       -3     
- Misses        690      718      +28     

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