CI: Speed improvements

[tony]

tmux-python/libtmux#428

• ci(codeql-analysis): Update action versions, cleanup
• Move pypi upload action out into separate job dependent on tests passing, only ran on git tags

[codecov]

Codecov Report

Merging #416 (b117d01) into master (6d0d2fd) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #416   +/-   ##
=======================================
  Coverage   61.19%   61.19%           
=======================================
  Files          35       35           
  Lines        2760     2760           
  Branches      662      662           
=======================================
  Hits         1689     1689           
  Misses        642      642           
  Partials      429      429           

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[tony]

https://github.com/tmux-python/libtmux/pulls?q=is%3Apr+is%3Aclosed

• This now runs release in a separate job, only if tests pass
• Avoids superfluously fetching docker image each push (shaves ~30s off ci run time)