project.config: grant submit access to the 1.22 release branch

For go.dev/issue/64340.

Change-Id: Ifcc81661c468d6d6209718263a48906c48de1bd5
Reviewed-on: https://go-review.googlesource.com/c/All-Projects/+/556980
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>