Update golang.org/x dependencies to their latest tagged versions.

Change-Id: Ifd5a045d97093611d3d2b9e114e95d5253edbf01
Reviewed-on: https://go-review.googlesource.com/c/text/+/788100
LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>