bump atc ifrit

[finishes #80072024]

Submodule src/github.com/concourse/atc dc1ba85..677776d:
  > only one atc scans for resources at a time
Submodule src/github.com/tedsuo/ifrit d74e1e6..eb3011f:
  > Merge pull request #6 from Zteve/master
  > added Interrupt and Kill helpers to ginkgomon.
  > sliding buffer tests
  > static split into two files for clarity.
  > add ginkgomon.Invoke helper
  > ginkgomon: exit with failure on a failed start
  > restarter does not block on invoke
  > ginkgomon propogates signals while detecting the start check
  > ginkgomon is a gomega.Exiter