Use oalders/es-5 branch in CircleCI

Author: oalders

Diff for: .circleci/config.yml

@@ -21,6 +21,7 @@ jobs:
           command: |
             git clone https://github.com/metacpan/metacpan-docker.git
             cd metacpan-docker
+            git switch oalders/es-5
           name: metacpan-docker checkout
       - checkout:
           path: metacpan-docker/src/metacpan-api