fix broken gcp page

Author: jordanstephens

docs/tutorials/deploying-from-github-actions/to-gcp.mdx

@@ -2,6 +2,8 @@
 title: Deploying to GCP
 description: Using the Defang Github Action to deploy your project to GCP from your CI/CD pipeline.
 ---
+import Tabs from '@theme/Tabs';
+import TabItem from '@theme/TabItem';
 
 # Deploying to GCP from GitHub Actions