build(deps): bump codecov/codecov-action in the actions group (#676)

Bumps the actions group with 1 update: [codecov/codecov-action](https://github.com/codecov/codecov-action).


Updates `codecov/codecov-action` from 4 to 5
- [Release notes](https://github.com/codecov/codecov-action/releases)
- [Changelog](https://github.com/codecov/codecov-action/blob/main/CHANGELOG.md)
- [Commits](codecov/codecov-action@v4...v5)

---
updated-dependencies:
- dependency-name: codecov/codecov-action
  dependency-version: '5'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: actions
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/tests.yml

@@ -103,7 +103,7 @@ jobs:
 
     # TEMPORARY FIX: Disable codecov until we can get it working again
     - name: Upload to Codecov
-      uses: codecov/codecov-action@v4
+      uses: codecov/codecov-action@v5
       if: false
       with:
         name: myst-nb-pytests