Update Docker version

This fixes an issue with the version of Alpine we're using:
6 years ago · fe69061c0c
1 changed files with 1 additions and 1 deletions
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@ -3,7 +3,7 @@ jobs:
  build:
    working_directory: /app
    docker:
-      - image: docker:17.05.0-ce-git
+      - image: docker:18.06.1-ce-git
    steps:
      - checkout
      - setup_remote_docker