fix location

Author: xlc

.github/workflows/polka-codes-review-pr.yml

@@ -42,5 +42,5 @@ jobs:
           POLKA_API_PROVIDER: google-vertex
           POLKA_MODEL: gemini-3-pro-preview
           GITHUB_TOKEN: ${{ github.token }}
-          GOOGLE_VERTEX_LOCATION: us-central1
+          GOOGLE_VERTEX_LOCATION: global
           GOOGLE_VERTEX_PROJECT: ${{ secrets.GOOGLE_VERTEX_PROJECT }}