bump atc
bump atc

[finishes #114162873]

Submodule src/github.com/concourse/atc 7ce2646..0ce2a52:
  > inputMappings > inputMapping, outputMappings > outputMapping
  > use output_mappings to map outputs in pipeline config

Signed-off-by: Maria Shaldibina <dc03896a0185453e5852a5e0f0fab6cbd2e026ff@pivotal.io>

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