bump fly
bump fly

[finishes #93710648]

Submodule src/github.com/concourse/fly 77b3f40..cbf5199:
  > strip trailing slashes from targets in .flyrc

Signed-off-by: Toby Rumans <516e7840355d33b790e9dc5c111fe7c7c270a08f@pivotal.io>

concourse/concourse,sedouard/concourse,CloudCredo/concourse,sedouard/concourse,holgero/concourse,CloudCredo/concourse,jbayer/concourse,jbayer/concourse,longnguyen11288/concourse,Amit-PivotalLabs/concourse,concourse/concourse,squeedee/concourse,squeedee/concourse,Amit-PivotalLabs/concourse,cjcjameson/concourse,beni55/concourse,concourse/concourse,concourse/concourse,zachgersh/concourse,beni55/concourse,cjcjameson/concourse,squeedee/concourse,concourse/concourse,sedouard/concourse,jbayer/concourse,zachgersh/concourse,longnguyen11288/concourse,Amit-PivotalLabs/concourse,CloudCredo/concourse,longnguyen11288/concourse,holgero/concourse,cjcjameson/concourse,beni55/concourse,holgero/concourse,zachgersh/concourse