Update CI/CD pipelines Part 1

[dennisbader]

Checklist before merging this PR:

• Mentioned all issues that this PR fixes or addresses.
• Summarized the updates of this PR under Summary.
• Added an entry under Unreleased in the Changelog. (will do that in next PRs)

addresses #1467, #586, #689

Summary

This is first of multiple PRs to improve or CI/CD workflows (and remove gradle as a dependencies)

• Fixes failing macOS pipeline
• removes gradle dependency from develop and merge workflows
• improves caching:
  • Adds update-cache workflow which is triggered on every merge into master:
    • caches python environment on master branch so that other workflows in new branches can use them (see here for more info).
  • docs and example checks now leverage cache as well

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.88%. Comparing base (ad93612) to head (d5db286).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2577      +/-   ##
==========================================
- Coverage   93.89%   93.88%   -0.02%     
==========================================
  Files         139      139              
  Lines       14888    14874      -14     
==========================================
- Hits        13979    13964      -15     
- Misses        909      910       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[dennisbader]

Merging this to validate merge and update-cache workflows