Fix number of days in stalebot message (#12050)

Author: sbc100

.github/stale.yml

@@ -12,7 +12,7 @@ staleLabel: wontfix
 markComment: >
   This issue has been automatically marked as stale because there has been no
   activity in the past year.  It will be closed automatically if no further
-  activity occurs in the next 7 days.  Feel free to re-open at any time if this
+  activity occurs in the next 30 days.  Feel free to re-open at any time if this
   issue is still relevant.
 # Comment to post when closing a stale issue. Set to `false` to disable
 closeComment: false