Bump codecov/codecov-action from 5 to 6 in the actions group (#152)

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


Updates `codecov/codecov-action` from 5 to 6
- [Release notes](https://github.com/codecov/codecov-action/releases)
- [Changelog](https://github.com/codecov/codecov-action/blob/main/CHANGELOG.md)
- [Commits](codecov/codecov-action@v5...v6)

---
updated-dependencies:
- dependency-name: codecov/codecov-action
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: actions
...

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

Author: dependabot[bot]

.github/workflows/tests.yml

@@ -45,7 +45,7 @@ jobs:
       # this is why we run `coverage xml` afterwards (required by codecov)
     - name: Upload to Codecov
       if: github.repository == 'executablebooks/jupyter-cache' && matrix.python-version == '3.10' && matrix.os == 'ubuntu-latest' && false
-      uses: codecov/codecov-action@v5
+      uses: codecov/codecov-action@v6
       with:
         name: jupyter-cache-pytests-py3.10
         flags: pytests