This commit will be tagged v0.57.0.

Change-Id: Ie8cd607757d2ddfc84f2ef7e8f48a527a2dfa868
Reviewed-on: https://code-review.googlesource.com/c/gocloud/+/55810
Reviewed-by: kokoro <[email protected]>
Reviewed-by: Tyler Bui-Palsulich <[email protected]>