Update/actions

[zorkow]

PR updates all github actions to latest available versions. In particular, we now use pnpm v12 and node v26 for tests.

• For pnpm we now use the latest, shortened syntax suggested in the README here. Consequently, this is now at v3 (not v5 for the previous syntax.
• For checkout and codecov we are now at v7.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.13%. Comparing base (3fcfca2) to head (d418c73).

Additional details and impacted files

@@            Coverage Diff             @@
##           develop    #1575     +/-   ##
==========================================
  Coverage    87.13%   87.13%             
==========================================
  Files          392      392             
  Lines        89279    89279             
  Branches      3385     5079   +1694     
==========================================
  Hits         77793    77793             
+ Misses       11486    11465     -21     
- Partials         0       21     +21     

☔ View full report in Codecov by Harness.
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🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[dpvc]

Looks good. Thanks for taking care of that.