Bump codecov/codecov-action from 3 to 4 (#312)

* 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]>

Necessary fixes:
* add secret to env
* fix trailing comma

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: k-dominik <[email protected]>

Author: dependabot[bot]

.github/workflows/test.yml

@@ -42,12 +42,14 @@ jobs:
         # auto activation of env does not seem to work on win
         run: >-
           pip install -e . && pytest
-      - uses: codecov/codecov-action@v3
+      - uses: codecov/codecov-action@v4
         if: matrix.os == 'ubuntu-latest'
         with:
-          files: ./coverage.xml,
+          files: ./coverage.xml
           fail_ci_if_error: true # optional (default = false)
           verbose: true # optional (default = false)
+        env:
+          CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
 
   test-w-conda-recipe:
     strategy: