Combine test and coverage, and cache pre-commit install

[sondrelg]

Small upgrade before copying repo.

• Combines the coverage and test workflows to deduplicate work.
• Caches the pre-commit cache for the linting job, which cuts the runtime by ~20 sec
• Updates the pre-commit config
• Updates dependencies

[codecov]

Codecov Report

Merging #68 (487ee38) into master (37a07b9) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master       #68   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           19        19           
  Lines          345       343    -2     
=========================================
- Hits           345       343    -2     

Impacted Files	Coverage Δ
django_guid/config.py	100.00% <0.00%> (ø)

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[JonasKs]

🚀