Github action use checkout action v4

Author: xor-gate

.github/workflows/build-syncthing-macos.yml

@@ -28,7 +28,7 @@ jobs:
           make debug
 
       - name: Archive artifacts
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: syncthing-macos-debug
           path: Build/Products/Debug/Syncthing.app