go.mod: update golang.org/x dependencies

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

Change-Id: I54f980bf305343cdd4c3330b92dbf089b25f6a62
Reviewed-on: https://go-review.googlesource.com/c/benchmarks/+/702036
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Mark Freeman <markfreeman@google.com>
Auto-Submit: Gopher Robot <gobot@golang.org>