Fix missing quote

Author: be5invis

.github/workflows/stale.yml

@@ -1,7 +1,7 @@
 name: 'Close stale issues and PRs'
 on:
   schedule:
-    - cron: '0 6 * * *'
+    - cron: '0 7 * * *'
 
 jobs:
   stale:
@@ -13,4 +13,4 @@ jobs:
           stale-issue-message: 'This issue is stale because it has been open 60 days with no activity. Remove stale label or comment or this will be closed in 15 days.'
           days-before-stale: 60
           days-before-close: 15
-          exempt-milestones: 'backlog,research
+          exempt-milestones: 'backlog,research'