ci: Run publishing workflow only on success

Author: kkrypt0nn

.github/workflows/publish.yml

@@ -18,6 +18,7 @@ jobs:
       url: https://pypi.org/p/pymanuf
     permissions:
       id-token: write
+    if: ${{ github.event.workflow_run.conclusion == 'success' }}
     steps:
       - name: Checkout source code
         uses: actions/checkout@v4