Update actions/upload-artifact action to v5

Author: renovate[bot]

.github/workflows/ci.yml

@@ -54,7 +54,7 @@ jobs:
         run: task test
 
       - name: Upload build artifacts
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v5
         with:
           name: ocireg-mcp
           path: build/ocireg-mcp