Swith to https only for forked registry source

.custom_sources.yml

@@ -23,7 +23,7 @@ omnibus:
   remote: "https://dev.gitlab.org/gitlab/omnibus.git"
   alternative: "https://gitlab.com/gitlab-org/omnibus.git"
 registry:
-  remote: "git@gitlab.com:twk3/docker-distribution.git"
+  remote: "https://gitlab.com/twk3/docker-distribution.git"
   alternative: "https://gitlab.com/twk3/docker-distribution.git"
 rb-readline:
   remote: "git@dev.gitlab.org:omnibus-mirror/rb-readline.git"