Set ignore-already-exists-error to true

Author: philwebb

.github/actions/sync-to-maven-central/action.yml

@@ -28,6 +28,7 @@ runs:
       with:
         token: ${{ inputs.central-token-password }}
         token-name: ${{ inputs.central-token-username }}
+        ignore-already-exists-error: true
     - name: Await
       uses: ./.github/actions/await-http-resource
       with: