bump topgun
bump topgun

Submodule src/github.com/concourse/topgun 1874f6af...70e11a42:
  > remove bind-mounting certs test
  < delete old cache volumes when new resource version
  < add tests for inactive resource
  < unpend bind mount certificates test
  < fix http proxy + image artifact tests
  < fix package name
  < move image artifact tests from testflight
  < move proxy test over from testflight
  < localize var
  < fix containers_scoped_to_team_test
  < Revert "unpend hijack check container test"
  < query containers via fly, not database
  < unfocus :(
  < add test for tagged resource checking
  < darwin captures whitespace here
  < unpend hijack check container test
  < pend bind mounts test
  < Merge branch 'releases/2.7'
  < pend atc shutdown test
  < added support for an arbitary number of topgun networks
  < Randomizing the topgun deployment name
  < force stringification of stemcell version
  < test transferring artifacts between workers
  < fix topgun test for atc shutdown
  < resource_caches > worker_resource_caches
  < skip hijacking to check containers test
  < only task containers are kept around
  < hijacking a task no longer asks about check/get
  < validate getting containers succeeds

Signed-off-by: Clara Fu <d5c8bdbc15689555c92563892e959c79b3fc425f@pivotal.io>

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