bump to 5.2.1
bump to 5.2.1

gitlabhq/gitlab-ci-runner,andrewmunsell/gitlab-ci-runner,gitlabhq/gitlab-ci-runner,mfittko/gitlab-ci-runner,andrewmunsell/gitlab-ci-runner,cui-liqiang/gitlab-ci-runner,mfittko/gitlab-ci-runner,cui-liqiang/gitlab-ci-runner