Update actions/upload-artifact action to v6

Author: xdev-renovate

.github/workflows/check-build.yml

@@ -69,7 +69,7 @@ jobs:
         fi
 
     - name: Upload demo files
-      uses: actions/upload-artifact@v5
+      uses: actions/upload-artifact@v6
       with:
         name: demo-files-java-${{ matrix.java }}
         path: ${{ env.DEMO_MAVEN_MODULE }}/target/${{ env.DEMO_MAVEN_MODULE }}.jar
@@ -152,7 +152,7 @@ jobs:
 
     - name: Upload report
       if: always()
-      uses: actions/upload-artifact@v5
+      uses: actions/upload-artifact@v6
       with:
         name: pmd-report
         if-no-files-found: ignore