Update verifyFreezePeriod.yml to ignore milestone promotions

.github/workflows/verifyFreezePeriod.yml

@@ -19,7 +19,7 @@ jobs:
           calId="[email protected]"
           calURL="https://clients6.google.com/calendar/v3/calendars/group.calendar.google.com/events?calendarId=${calId}&singleEvents=true&timeZone=UTC&maxResults=250&sanitizeHtml=true&timeMin=${today}T00:00:00Z&timeMax=${tomorrow}T00:00:00Z&key=AIzaSyBNlYH01_9Hc5S1J9vuFmu2nUqBZJNAXxs"
           echo "Querying calendar https://calendar.google.com/calendar/u/0/embed?src=${calId}"
-          curl "${calURL}" | grep -i -e "stabilization" -e "signoff" -e "promotion"
+          curl "${calURL}" | grep -i -P '(stabilization|signoff|(?<!M\d) promotion)'
           if [[ $? == 0 ]]; then
             echo "::error::Today is a freeze day"
             exit 1 #Exiting with non-0 makes this workflow fail