CI Update

[Erotemic]

Performs CI updates and minor cleanups:

• Removes old Python constructs
• Use UV in the CI wherever possible
• Bump version to 4.3.0 in anticipation of new changes.
• Add codepsell to pyproject.toml and fix simple spelling errors

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.32%. Comparing base (cc2abf1) to head (0bbcdf9).
Report is 37 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #324      +/-   ##
==========================================
+ Coverage   60.28%   61.32%   +1.03%     
==========================================
  Files          11       11              
  Lines         851      848       -3     
  Branches      198      186      -12     
==========================================
+ Hits          513      520       +7     
+ Misses        283      274       -9     
+ Partials       55       54       -1     

Files with missing lines	Coverage Δ
line_profiler/__init__.py	100.00% <100.00%> (ø)
line_profiler/line_profiler.py	56.37% <100.00%> (+1.89%)	⬆️

... and 5 files with indirect coverage changes

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