update shelf_packages_handler to the latest version
update shelf_packages_handler to the latest version

Bug: https://github.com/dart-lang/package_resolver/issues/30
Change-Id: I42c10dabfb14f082b2facc492dd90c1ecdd1901a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/138386
Auto-Submit: Jake Macdonald <28dccc213a1e50b0de348b9cb82c0229ef6b65f0@google.com>
Commit-Queue: Jake Macdonald <28dccc213a1e50b0de348b9cb82c0229ef6b65f0@google.com>
Commit-Queue: Nate Bosch <dc212c74d8afde9c690fdd09e74d3e5c5d5a3de0@google.com>
Reviewed-by: Nate Bosch <dc212c74d8afde9c690fdd09e74d3e5c5d5a3de0@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