Remove stale bot to operate on PRs (#1059)

Author: ThomsonTan

.github/workflows/stale.yml

@@ -1,4 +1,4 @@
-name: 'Mark and close stale issues and PRs'
+name: 'Mark and close stale issues'
 on:
   schedule:
     - cron: '30 1 * * *'
@@ -9,8 +9,8 @@ jobs:
     steps:
       - uses: actions/stale@v4
         with:
-          stale-issue-message: 'This issue was marked as stale due to lack of activity. It will be closed in 7 days.'
+          stale-issue-message: 'This issue was marked as stale due to lack of activity. It will be closed in 7 days if no furthur activity occurs.'
           close-issue-message: 'Closed as inactive. Feel free to reopen if this is still an issue.'
-          days-before-stale: 60
-          days-before-close: 7
+          days-before-issue-stale: 60
+          days-before-issue-close: 7
           exempt-pr-labels: 'do-not-stale'