Merge branch 'update-ruby-in-gitlab-qa-alpine-image' into 'master'

Update Ruby to 2.6.3 in the gitlab-qa-alpine image

See merge request gitlab-org/gitlab-build-images!233

Dockerfile.gitlab-qa-alpine

@@ -3,7 +3,7 @@
 #  - Nightly QA: https://gitlab.com/gitlab-org/quality/nightly/blob/master/.gitlab-ci.yml
 #  - Staging QA: https://gitlab.com/gitlab-org/quality/staging/blob/master/.gitlab-ci.yml
 
-FROM ruby:2.5.3-alpine
+FROM ruby:2.6.3-alpine
 MAINTAINER GitLab Quality Team
 
 WORKDIR /home/qa