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

Change-Id: I02eb549b47bf711f9c70b10ef33f619c19129bee
Reviewed-on: https://go-review.googlesource.com/c/text/+/633477
Reviewed-by: David Chase <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
Auto-Submit: Gopher Robot <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>