Update makefile
Update makefile

- Drop -f from docker tag, since that flag is deprecated.
- Assume $(TAG)/Dockerfile is always out of date, since it depends on
  `config.mk`, which itself could depend on anything. In practice, we
  don't lose any performance there, since a) regenerating that file is
  cheap and b) build is already phony (but has Docker caching).

aptible/docker-postgresql,fancyremarker/docker-postgresql,fancyremarker/docker-postgresql,aptible/docker-postgresql,fancyremarker/docker-postgresql,aptible/docker-postgresql