Bump codecov/codecov-action from 6 to 7 (#71)

Bumps [codecov/codecov-action](https://github.com/codecov/codecov-action) from 6 to 7.
- [Release notes](https://github.com/codecov/codecov-action/releases)
- [Changelog](https://github.com/codecov/codecov-action/blob/main/CHANGELOG.md)
- [Commits](codecov/codecov-action@v6...v7)

---
updated-dependencies:
- dependency-name: codecov/codecov-action
  dependency-version: '7'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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/continuous-integration.yml

@@ -78,7 +78,7 @@ jobs:
       run: python -m pytest --cov=pyspod --cov-report=xml tests/ --with-mpi -v
 
     - name: Upload coverage to Codecov
-      uses: codecov/codecov-action@v6
+      uses: codecov/codecov-action@v7
       with:
         token: ${{ secrets.CODECOV_TOKEN }}
         fail_ci_if_error: true