Bump dart-lang/setup-dart from 1.5.1 to 1.6.0 Closes https://github.com/dart-lang/flute/pull/8 GitOrigin-RevId: 35f84581a3d303e0144a5bd04d5022862c44e163 Change-Id: Id294172d6ea8481cbfa85ed57022a5a3b55b5863 Reviewed-on: https://dart-review.googlesource.com/c/flute/+/333049 Reviewed-by: Alexander Thomas <athom@google.com>