ci: use github.event.label.name for check in pull-request-commenter

The `github.event.label.name` was replaced by
`github.event.pull_request.label` in PR ceph#3862. It seems that the value
always is `null`, which causes the pull-request-commenter to skip the
events for `ok-to-test` label additions. By using the original
`github.event.label.name`, things work again as expected.

Signed-off-by: Niels de Vos <ndevos@ibm.com>

.github/workflows/pull-request-commentor.yaml

@@ -12,7 +12,7 @@ on:
 jobs:
   add-comment:
     if: >
-      (github.event.pull_request.label == 'ok-to-test' &&
+      (github.event.label.name == 'ok-to-test' &&
       github.event.pull_request.merged != true) ||
       (github.event.pull_request.action == 'opened' &&
       contains(github.event.pull_request.labels.*.name,'ok-to-test'))