message: repokitteh: pin modules to git SHAs.
  The main goal here is to improve stability via hermetic description of RK dependencies.
diff: -use("github.com/repokitteh/modules/assign.star")
  -use("github.com/repokitteh/modules/review.star")
  -use("github.com/repokitteh/modules/wait.star")
  -use("github.com/repokitteh/modules/circleci.star", secret_token=get_secret('circle_token'))
  +use("github.com/repokitteh/modules/assign.star#22520d03464dd9503e036c7fa365c427723c4aaf")
  +use("github.com/repokitteh/modules/review.star#22520d03464dd9503e036c7fa365c427723c4aaf")
  +use("github.com/repokitteh/modules/wait.star#22520d03464dd9503e036c7fa365c427723c4aaf")
  +use("github.com/repokitteh/modules/circleci.star#22520d03464dd9503e036c7fa365c427723c4aaf", secret_token=get_secret('circle_token'))
  use(
  - "github.com/repokitteh/modules/ownerscheck.star",
  + "github.com/repokitteh/modules/ownerscheck.star#22520d03464dd9503e036c7fa365c427723c4aaf",
  paths=[
  {
  "owner": "envoyproxy/api-shepherds!",
  