github: do not automatically merge on "extended-review" label
github: do not automatically merge on "extended-review" label

The "extended-review" label indicates that review is likely to take
an extended period of time and for bots to not automatically take
a PR.

This avoid the need to preemptively mark a PR as changes needed or
give a false impression with a "do-not-merge" tag, which has a subtle
lack-of-quality implication.

Signed-off-by: John Mulligan <eda8ad33169deab44f9fe65847f99e368da6c91b@redhat.com>

ceph/go-ceph,ceph/go-ceph,ceph/go-ceph