Update deprecated github action

Author: berndbr

.github/workflows/dotnet-core.yml

@@ -115,7 +115,7 @@ jobs:
         
     - name: Upload artifacts
       if: github.event_name == 'push' && (contains(github.ref, 'refs/tags/') || contains(github.ref, 'refs/heads/master'))
-      uses: actions/upload-artifact@v2
+      uses: actions/upload-artifact@v4
       with:
         name: SmartApplicationFramework-${{ steps.minver.outputs.version }}
         path: ./artifacts