[ci] Update codecov/codecov-action to v4.

Signed-off-by: Michael Seifert <[email protected]>

Author: seifertm

.github/workflows/main.yml

@@ -118,7 +118,7 @@ jobs:
         coverage combine
         coverage xml
     - name: Upload coverage report
-      uses: codecov/codecov-action@v3
+      uses: codecov/codecov-action@v4
       with:
         files: coverage.xml
         fail_ci_if_error: true