Update to the latest package:shelf
Update to the latest package:shelf

Use the commit SHA rather than a tagged version.

Change-Id: I2de82f1e4057a45f65b0041246f7bef097b65642
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/157479
Commit-Queue: Nate Bosch <dc212c74d8afde9c690fdd09e74d3e5c5d5a3de0@google.com>
Auto-Submit: Nate Bosch <dc212c74d8afde9c690fdd09e74d3e5c5d5a3de0@google.com>
Reviewed-by: Kevin Moore <1d6e7d10d051cf619c5282da3c28fd8d3e0a65a4@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