skip dev deployment when credentials are not available

skip dev deployment when credentials are not available.  This can happen when pull requests come from external repositories.

.github/workflows/azure-static-web-apps-polite-dune-0c657411e.yml

@@ -37,6 +37,8 @@ jobs:
           output_location: "dist/" # Built app content directory - optional
           app_build_command: "npm run build-dev"
           ###### End of Repository/Build Configurations ######
+        env:
+          SKIP_DEPLOY_ON_MISSING_SECRETS: true
 
   close_pull_request_job:
     if: github.event_name == 'pull_request' && github.event.action == 'closed'
@@ -49,3 +51,5 @@ jobs:
         with:
           azure_static_web_apps_api_token: ${{ secrets.AZURE_STATIC_WEB_APPS_API_TOKEN_POLITE_DUNE_0C657411E }}
           action: "close"
+        env:
+          SKIP_DEPLOY_ON_MISSING_SECRETS: true