Improve the GitHub workflow to prevent premature email notifications
about missing labels. Previously, contributors without write permissions
to the scylladb repo would receive immediate notification emails about
missing required backport labels, even if they were in the process of
adding them.
This change introduces a 1-minute grace period before checking for
required labels, giving contributors sufficient time to add necessary
labels (like backport labels) to their pull requests before any warning
notifications are sent.
The delay makes the experience more user-friendly for non-maintainer
contributors while maintaining the labeling requirements.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#23539