bump atc
bump atc

[finishes #108024032]

Submodule src/github.com/concourse/atc 7e2960d..a4a055b:
  > check if closing the event stream failed
  > use client to get pipeline config

Signed-off-by: Chris Brown <eb0819782e2e967e3d4f4d71eab0c647ed2659cf@pivotal.io>
Signed-off-by: Anand Gaitonde <4f0ff06b2390eeadb0769d298cbdb3dc6df4c73d@pivotal.io>

longnguyen11288/concourse,concourse/concourse,concourse/concourse,concourse/concourse,concourse/concourse,concourse/concourse,longnguyen11288/concourse,cjcjameson/concourse,cjcjameson/concourse,longnguyen11288/concourse,zachgersh/concourse,zachgersh/concourse,cjcjameson/concourse,zachgersh/concourse