x509roots/fallback: update bundle

This is an automated CL which updates the NSS root bundle.

Change-Id: Ic5267bf9d66b676e1cfc5fc2ae153afb8f33b29c
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/631635
Auto-Submit: Gopher Robot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Roland Shoemaker <roland@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

Author: gopherbot