stale.yml: use stale as the stale label name.

Author: MikeMcQuaid

.github/stale.yml

@@ -9,7 +9,7 @@ exemptLabels:
   - pinned
   - security
 # Label to use when marking as stale
-staleLabel: wontfix
+staleLabel: stale
 # Comment to post when marking as stale. Set to `false` to disable
 markComment: >
   This issue has been automatically marked as stale because it has not had