Docker build all tags starting vX.Y.Z, inc RCs

Note the regex must match the complete string anyway,
so the leading ^ was useless.

.circleci/config.yml

@@ -156,7 +156,7 @@ workflows:
       - dockerhubuploadrelease:
           filters:
             tags:
-              only: /^v[0-9].[0-9]+.[0-9]+(.[0-9]+)?/
+              only: /v[0-9].[0-9]+.[0-9]+.*/
             branches:
               ignore: /.*/
       - dockerhubuploadlatest: