Try to fix scheduled workflow (#664)

This workflow isn't running automatically. This might be because I added
a manual workflow_dispatch option when I introduced it. Try removing it
and putting it back to nightly to see if it runs.

Author: zetter-rpf

.github/workflows/close_stale_issues_and_prs.yml

@@ -1,8 +1,7 @@
 name: 'Close stale issues and PRs'
 on:
   schedule:
-    - cron: '0 * * * *'
-  workflow_dispatch:
+    - cron: '0 3 * * *'
 
 permissions:
   actions: write
@@ -23,4 +22,4 @@ jobs:
           days-before-issue-stale: 90
           days-before-pr-stale: 30
           days-before-issue-close: 7
-          days-before-pr-close: 7
+          days-before-pr-close: 7