fix: update pygfx pinnings

[tlambert03]

this fixes some hard errors I'm getting on a recent resync (our lockfile was preventing it from showing... but since this is a library not an app, that lockfile doesn't protect end users). This PR

• removes the lockfile
• fixes the pyfgx errors
• specifically allows rendercanvas to leak widgets (since something has changed and they now seem to have an internal strong reference that prevents cleanup)
• pins pygfx/wgpu/rendercanvas, since they still change relatively often as they develop.

cc @gselzer ... you ok with these changes?

---

edit: this PR morphed. #235 is doing most of the change, now this is just here to try to update pygfx/rendercanvas/wgpu... but that turned into a bigger issue.

[gselzer]

Yeah, I think these are all fine. Good to pin pygfx + friends for now. Especially love getting rid of the lockfile!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.14%. Comparing base (50ce7b5) to head (de5e767).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #234      +/-   ##
==========================================
- Coverage   85.98%   85.14%   -0.85%     
==========================================
  Files          46       46              
  Lines        5224     5229       +5     
==========================================
- Hits         4492     4452      -40     
- Misses        732      777      +45     

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[tlambert03]

thanks. also dropping python 3.9, which triggered a lot of autoformat changes

[tlambert03]

closed by #239