circle config: minor bug fix

.circleci/config.yml

@@ -57,7 +57,7 @@ jobs:
       - run:
           name: Deploy
           command: |
-            echo $$CIRCLE_BRANCH
+            echo $CIRCLE_BRANCH
             if [ $CIRCLE_BRANCH = "main" ]; then
               echo $FLASK_SECRET_KEY > flask_secret_key
               echo $GCLOUD_SERVICE_KEY | gcloud auth activate-service-account --key-file=-