bump atc
bump atc

[finishes #111714068]

Submodule src/github.com/concourse/atc 9d06078..6acfce7:
  > bump elm-ansi to fix node output; fix versions UI

cjcjameson/concourse,cjcjameson/concourse,zachgersh/concourse,concourse/concourse,concourse/concourse,zachgersh/concourse,concourse/concourse,concourse/concourse,concourse/concourse,zachgersh/concourse,cjcjameson/concourse