message: Update Tinkey URL and hash for Tink 1.6.0.
diff: class Tinkey < Formula
  desc "A command line tool to generate and manipulate keysets for the Tink cryptography library"
  homepage "https://github.com/google/tink/tree/master/tools/tinkey"
  - url "https://storage.googleapis.com/tinkey/tinkey-1.5.0.tar.gz"
  - sha256 "bd148e684ffba85b8499bcfe29c8ed1e9dedef52eddd35dabb0a34e396790b90"
  + url "https://storage.googleapis.com/tinkey/tinkey-1.6.0.tar.gz"
  + sha256 "51d9694a704d00fbac04862a6427ad5f17bf59f91d5e963517d8799141e737c0"
  bottle :unneeded
  