Limit GESIS dispatcher to main repository

Author: rgaiacs

.github/workflows/gesis.yaml

@@ -10,6 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Dispatcher
+        if: github.repository == 'jupyterhub/mybinder.org-deploy'
         env:
           GESIS_TOKEN: ${{ secrets.GESIS_TOKEN }}
         run: |