Delete stale.yml

A stale issue is unlikely to actually be solved. Stale PRs should be handled manually.

https://news.ycombinator.com/item?id=28998374

.github/workflows/stale.yml

@@ -1,25 +0,0 @@
-# This workflow warns and then closes issues and PRs that have had no activity for a specified amount of time.
-#
-# You can adjust the behavior by modifying this file.
-# For more information, see:
-# https://github.com/actions/stale
-name: Mark stale issues and pull requests
-
-on:
-  schedule:
-  - cron: '43 1 * * *'
-
-jobs:
-  stale:
-
-    runs-on: ubuntu-latest
-    permissions:
-      issues: write
-      pull-requests: write
-
-    steps:
-    - uses: actions/stale@v3
-      with:
-        repo-token: ${{ secrets.GITHUB_TOKEN }}
-        stale-issue-message: "This looks stale!"
-        stale-pr-message: "This looks stale!"