Update actions/stale from v7 to v8 and disable it for pull request

.github/workflows/stale-bot.yml

@@ -1,4 +1,4 @@
-name: 'Automatically close stale issues and PRs'
+name: 'Automatically close stale issues'
 on:
   workflow_dispatch:
   schedule:
@@ -9,14 +9,14 @@ jobs:
   stale:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/stale@v7
+      - uses: actions/stale@v8
         with:
           stale-issue-message: 'We are clearing up our old issues and your ticket has been open for 3 months with no activity. Remove stale label or comment or this will be closed in 2 days.'
           close-issue-message: 'This issue was closed because it has been stalled for 2 days with no activity.'
           days-before-stale: 90
           days-before-close: 2
-          days-before-pr-stale: 999999999
-          days-before-pr-close: 1
+          days-before-pr-stale: -1
+          days-before-pr-close: -1
           exempt-issue-labels: 'News,Medium,High,discussion,bug,doc,feature-request'
           exempt-issue-assignees: 'louislam'
           operations-per-run: 200