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

Change-Id: I79a762b016aa660c10f8c05557a79b05e98f695b
Reviewed-on: https://go-review.googlesource.com/c/net/+/813281
Auto-Submit: Gopher Robot <gobot@golang.org>
Reviewed-by: Mark Freeman <markfreeman@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>