Update to the latest package:yaml
Update to the latest package:yaml

Change-Id: Ic1fa3818492cb95fcee9ec82e8a9c7466bb870b0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/214501
Auto-Submit: Nate Bosch <dc212c74d8afde9c690fdd09e74d3e5c5d5a3de0@google.com>
Commit-Queue: Jonas Jensen <c9327fa216ae2ef84df7c55b809d4ba270141b48@google.com>
Reviewed-by: Jonas Jensen <c9327fa216ae2ef84df7c55b809d4ba270141b48@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk