Bump actions/cache to v4

[dulmandakh]

Description of the Change

This PR bumps actions/cache to v4, fixes depreciation warnings

Checklist

• PR only contains one change (considered splitting up PR)
• unit-test added
• documentation updated
• CHANGELOG.md updated (only for user relevant changes)
• author name in AUTHORS

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.18%. Comparing base (e34819a) to head (258d8f8).
Report is 9 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1516      +/-   ##
==========================================
- Coverage   97.41%   97.18%   -0.23%     
==========================================
  Files          34       34              
  Lines        2164     2201      +37     
==========================================
+ Hits         2108     2139      +31     
- Misses         56       62       +6     

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