prevent double writes to worker in GCS, port to newer GCP auth workflow

.github/workflows/build.yml

@@ -49,17 +49,21 @@ jobs:
         with:
           node-version: '16'
 
+      - id: 'auth'
+        uses: 'google-github-actions/auth@v0'
+        with:
+          credentials_json: '${{ secrets.GCS_TF_KEY }}'
+
       - name: Set up Cloud SDK
-        uses: google-github-actions/setup-gcloud@master
+        uses: google-github-actions/setup-gcloud@v0
         with:
           project_id: ${{ secrets.GCS_PROJECT_ID }}
-          service_account_key: ${{ secrets.GCS_TF_KEY }}
           export_default_credentials: true
 
       - name: Check if already deployed
         id: check
         run: |
-          gsutil stat gs://roleypoly-artifacts/workers/${{ github.sha }}/${{ matrix.worker }}.js \
+          gsutil stat gs://roleypoly-artifacts/workers/${{ github.sha }}/index.mjs \
             && echo ::set-output name=skip::1 \
             || echo ::set-output name=skip::0
 
@@ -90,7 +94,6 @@ jobs:
         with:
           path: packages/api/dist/index.mjs
           destination: roleypoly-artifacts/workers/${{ github.sha }}
-          credentials: ${{ secrets.GCS_TF_KEY }}
 
   docker_build:
     name: Docker Build & Publish
@@ -159,7 +162,7 @@ jobs:
     needs:
       - docker_build
       - worker_build
-    if: github.ref == 'refs/heads/main'
+    if: github.ref == 'refs/heads/main' || github.ref == 'refs/heads/miniflare'
     runs-on: ubuntu-latest
     steps:
       - name: Get Bot digest