Bugfix: Pin upload-artifact to v4

Author: danschmidt5189

.github/workflows/build.yml

@@ -150,7 +150,7 @@ jobs:
 
       - if: ${{ always() }}
         name: Upload build artifacts
-        uses: actions/upload-artifact
+        uses: actions/upload-artifact@v4
         with:
           name: GeoServer Build (${{ env.BUILD_SUFFIX }})
           path: artifacts/*