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] <[email protected]>

Author: dependabot[bot]

.github/workflows/run_tests_matlab.yml

@@ -59,7 +59,7 @@ jobs:
         command: cd(fullfile(getenv('GITHUB_WORKSPACE'), '.github', 'workflows')); run tests_matlab;
 
     - name: Code coverage
-      uses: codecov/codecov-action@v3
+      uses: codecov/codecov-action@v4
       with:
         file: coverage.xml
         flags: ${{ matrix.os }}_matlab-${{ matrix.version }}