Merge pull request #7 from buildkite/renovate/buildkite-docker-compose-3.x

Update buildkite plugin docker-compose to v3

Author: toolmantim

.buildkite/pipeline.yml

@@ -2,5 +2,5 @@ steps:
   - name: ":golang:"
     command: "./scripts/test.sh"
     plugins:
-      - docker-compose#v2.6.0:
+      - docker-compose#v3.0.0:
           run: app