Update actions/upload-artifact to v4

Author: jglim

.github/workflows/dotnet-desktop.yml

@@ -52,7 +52,7 @@ jobs:
 
     # Upload the completed build
     - name: Upload build artifacts
-      uses: actions/upload-artifact@v2
+      uses: actions/upload-artifact@v4
       with:
         name: VisualUnlockECU (Windows, ZIP)
         path: UnlockECU/VisualUnlockECU/bin/Release/net5.0-windows