bump atc
bump atc

concourse/concourse#1425

Submodule src/github.com/concourse/atc 128f051..381f0f6:
  > zoom to fit when changing pipelines

Signed-off-by: Chris Hendrix <f9e38fc3e1ff46784bdcadbf77d17f93932faf2c@pivotal.io>

concourse/concourse,concourse/concourse,concourse/concourse,concourse/concourse,concourse/concourse