Bump codecov/codecov-action from 3 to 4

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>

.github/workflows/testing.yaml

@@ -79,7 +79,7 @@ jobs:
 
             # https://github.com/codecov/codecov-action
             - name: "Upload coverage to Codecov"
-              uses: codecov/codecov-action@v3
+              uses: codecov/codecov-action@v4
               with:
                   fail_ci_if_error: false # optional (default = false)
                   # files: var/html/coverage/coverage.xml, # optional