change GAR login again

.github/workflows/_deployment.yml

@@ -15,19 +15,13 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
 
-      - name: Google Auth
-        id: auth
-        uses: google-github-actions/auth@v2
-        with:
-          credentials_json: ${{ secrets.SERVICE_ACCOUNT_KEY_JSON }}
-
-      # https://github.com/docker/#-action/tree/v3?tab=readme-ov-file#google-artifact-registry-gar
-      - name: Login to Google Artifacts Registry
+      # https://github.com/docker/#-action/tree/v3?tab=readme-ov-file#service-account-based-authentication-1
+      - name: Login to GAR
         uses: docker/#-action@v2
         with:
           registry: ${{ vars.REGION }}-docker.pkg.dev
-          username: oauth2accesstoken
-          password: ${{ steps.auth.outputs.access_token }}
+          username: _json_key
+          password: ${{ secrets.SERVICE_ACCOUNT_KEY_JSON }}
 
       - name: Build, tag and push container
         id: build-image