build(deps): 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/travis.yml

@@ -86,6 +86,6 @@ jobs:
         pytest -v --cov nitransforms --cov-config .coveragerc --cov-report xml:cov.xml --doctest-modules nitransforms/
 
     - name: Submit code coverage
-      uses: codecov/codecov-action@v3
+      uses: codecov/codecov-action@v4
       with:
         files: cov.xml