Backport tox-dev/workflow bump to maint/11.0.x

[julianz-]

Updates the tox-dev/workflow to pick up the codecov/codecov-action bump required after Codecov migrated to a new GPG key following the acquisition by Harness. See PR #827

❓ What kind of change does this PR introduce?

• 🐞 bug fix
• 🐣 feature
• 📋 docs update
• 📋 tests/coverage improvement
• 📋 refactoring
• 💥 other

📋 Contribution checklist:

• I wrote descriptive pull request text above
• I think the code is well written
• I wrote [good commit messages]
• I have [squashed related commits together][related squash] after
  the changes have been approved
• Unit tests for the changes exist
• Integration tests for the changes exist (if applicable)
• I used the same coding conventions as the rest of the project
• The new code doesn't generate linter offenses
• Documentation reflects the changes
• The PR relates to only one subject with a clear title
  and description in grammatically correct, complete sentences

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.09%. Comparing base (7eced3d) to head (4fe79e1).
⚠️ Report is 2 commits behind head on maint/11.0.x.

Additional details and impacted files

@@               Coverage Diff                @@
##           maint/11.0.x     #829      +/-   ##
================================================
- Coverage         79.24%   78.09%   -1.16%     
================================================
  Files                29       41      +12     
  Lines              4197     4788     +591     
  Branches            538      547       +9     
================================================
+ Hits               3326     3739     +413     
- Misses              727      910     +183     
+ Partials            144      139       -5