Add support for jupyterlab 4

[painebot]

Uplift to latest pattern/tools/standards
fixes #264
fixes #229

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 85.24590% with 9 lines in your changes are missing coverage. Please review.

Project coverage is 84.84%. Comparing base (fd33902) to head (b08c6e3).
Report is 19 commits behind head on main.

Files	Patch %	Lines
nbcelltests/__main__.py	0.00%	2 Missing ⚠️
nbcelltests/__init__.py	66.66%	1 Missing ⚠️
nbcelltests/define.py	0.00%	1 Missing ⚠️
nbcelltests/extension.py	80.00%	1 Missing ⚠️
nbcelltests/lint/__init__.py	88.88%	1 Missing ⚠️
nbcelltests/shared.py	75.00%	1 Missing ⚠️
nbcelltests/test.py	83.33%	1 Missing ⚠️
nbcelltests/tests_vendored.py	90.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #272      +/-   ##
==========================================
- Coverage   84.96%   84.84%   -0.13%     
==========================================
  Files          16       15       -1     
  Lines        1197     1194       -3     
  Branches      123      123              
==========================================
- Hits         1017     1013       -4     
- Misses        159      160       +1     
  Partials       21       21              

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