[dependabot]: 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]>

.github/workflows/run-tests.yml

@@ -21,7 +21,7 @@ jobs:
     - run: pip install -ve .[tests] codespell tomli
     - run: make codespell-error
     - run: pytest mne_bids_pipeline -m "not dataset_test"
-    - uses: codecov/codecov-action@v3
+    - uses: codecov/codecov-action@v4
       if: success()
       name: 'Upload coverage to CodeCov'
   caching:
@@ -71,5 +71,5 @@ jobs:
       - run: pytest --cov-append -k ds003392 mne_bids_pipeline/
       - run: pytest --cov-append -k ds003392 mne_bids_pipeline/  # uses "mtime" method
         timeout-minutes: 1
-      - uses: codecov/codecov-action@v3
+      - uses: codecov/codecov-action@v4
         if: success()