Use Codecov GH action instead of bash script (#2706)

Co-authored-by: Konrad Windszus <konrad.windszus@netcentric.biz>

.github/workflows/maven.yml

@@ -91,9 +91,10 @@ jobs:
         with:
           check_name: Test report (${{ matrix.os }}, JDK ${{ matrix.jdk }})
 
+      # https://about.codecov.io/blog/javascript-code-coverage-using-github-actions-and-codecov/
       - name: Upload code coverage to CodeCov (Main build)
         if: matrix.isMainBuildEnv
-        run: bash <(curl -s https://codecov.io/bash)
+        uses: codecov/codecov-action@v2
 
       # https://github.com/marketplace/actions/changelog-enforcer
       - name: Enforce a changelog entry