ci: do_not_merge: add the manifest specific dnm label to the list

Add "DNM (manifest)" to the "do not merge" labels. This is meant to be a
DNM controlled by the manifest action specific, so that the normal one
can be used by humans and the two are not going to fight with each
other.

Signed-off-by: Fabio Baltieri <fabiobaltieri@google.com>

Author: fabiobaltieri

.github/workflows/do_not_merge.yml

@@ -11,6 +11,7 @@ jobs:
     steps:
       - name: Check for label
         if: ${{ contains(github.event.*.labels.*.name, 'DNM') ||
+                contains(github.event.*.labels.*.name, 'DNM (manifest)') ||
                 contains(github.event.*.labels.*.name, 'TSC') ||
                 contains(github.event.*.labels.*.name, 'Architecture Review') ||
                 contains(github.event.*.labels.*.name, 'dev-review') }}