ci: skip add-to-project workflow on forks

Author: martialziye

.github/workflows/add-to-project.yml

@@ -10,6 +10,7 @@ on:
 jobs:
   add-to-project:
     name: Add to project
+    if: ${{ !github.event.repository.fork }}
     runs-on: ubuntu-latest
     steps:
       - uses: actions/add-to-project@v1.0.2