chore: use from secrets instead of vars

Author: soedirgo

.github/workflows/preview-release.yml

@@ -94,7 +94,7 @@ jobs:
         id: generate-token
         uses: actions/create-github-app-token@v1
         with:
-          app-id: ${{ vars.CROSS_REPO_APP_ID }}
+          app-id: ${{ secrets.CROSS_REPO_APP_ID }}
           private-key: ${{ secrets.CROSS_REPO_APP_PRIVATE_KEY }}
           owner: supabase
           repositories: postgrest-js,supabase-js