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/test.yml

@@ -47,7 +47,7 @@ jobs:
           python -m pytest --cov=maestral --cov-report=xml tests/offline
 
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4
         with:
           file: ./coverage.xml
           flags: pytest
@@ -113,7 +113,7 @@ jobs:
           pytest -v --cov=maestral --cov-report=xml tests/linked/unit
 
       - name: Upload Code Coverage
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4
         with:
           file: ./coverage.xml
           flags: pytest
@@ -186,7 +186,7 @@ jobs:
           pytest --verbose --cov=maestral --cov-report=xml tests/linked/integration --fs-observer ${{ matrix.observer }}
 
       - name: Upload Code Coverage
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4
         with:
           file: ./coverage.xml
           flags: pytest