bump locket
bump locket

[finishes #155640891]

Submodule src/code.cloudfoundry.org/locket f304b67e..65c30701:
  > move the const definition to burglar to make check-metrics-documentation happy

cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release