Bump codecov/codecov-action from 3 to 4 (#745)

Bumps [codecov/codecov-action](https://github.com/codecov/codecov-action) from 3 to 4.
- [Release notes](https://github.com/codecov/codecov-action/releases)
- [Changelog](https://github.com/codecov/codecov-action/blob/main/CHANGELOG.md)
- [Commits](codecov/codecov-action@v3...v4)

---
updated-dependencies:
- dependency-name: codecov/codecov-action
  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>

.github/workflows/testing.yml

@@ -81,7 +81,7 @@
            pytest spaghetti -v -r a -n auto --cov spaghetti --doctest-modules --cov-report xml --color yes --cov-append --cov-report term-missing --timeout 60
        
        - name: codecov
-         uses: codecov/codecov-action@v3
+         uses: codecov/codecov-action@v4
          with:
            token: ${{ secrets.CODECOV_TOKEN }}
            file: ./coverage.xml