CI: Remove stalebot

PRs will now be fully owned by their respective author, so no need
automatically close them.

.github/workflows/stale.yml

@@ -1,37 +0,0 @@
-name: 'Close stale PRs'
-on:
-  # Run daily at 01:30.
-  schedule:
-    - cron: '30 1 * * *'
-
-  # Allows you to run this workflow manually from the Actions tab on GitHub.
-  workflow_dispatch:
-
-jobs:
-  stale:
-    runs-on: blacksmith-2vcpu-ubuntu-2404
-    if: github.repository == 'LadybirdBrowser/ladybird'
-    permissions:
-      actions: write  # required for cache management (see https://github.com/actions/stale/issues/1133)
-      pull-requests: write
-    steps:
-      - uses: actions/stale@eb5cf3af3ac0a1aa4c9c45633dd1ae542a27a899  # v10.3.0
-        with:
-          operations-per-run: 500
-
-          # Leave issues alone.
-          days-before-issue-stale: -1
-          days-before-issue-close: -1
-
-          # PRs become stale after 21 days of inactivity.
-          days-before-pr-stale: 21
-          stale-pr-label: stale
-          stale-pr-message: >
-            This pull request has been automatically marked as stale because it has not had recent activity. It will be
-            closed in 7 days if no further activity occurs. Thank you for your contributions!
-
-          # PRs get closed after 30 days (21 + 7) of inactivity
-          days-before-pr-close: 7
-          close-pr-message: >
-            This pull request has been closed because it has not had recent activity. Feel free to open a new pull
-            request if you wish to still contribute these changes. Thank you for your contributions!