add gh workflow for stale issues/PRs

.github/workflows/stale.yml

@@ -0,0 +1,26 @@
+name: Mark stale issues
+
+on:
+  schedule:
+    - cron: "30 1 * * *"
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  stale:
+    permissions:
+      issues: write  # for actions/stale to close stale issues
+      pull-requests: write  # for actions/stale to close stale PRs
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/stale@v3
+        with:
+          repo-token: ${{ secrets.GITHUB_TOKEN }}
+          stale-issue-message: "This issue is stale because it has been open 60 days with no activity. Remove stale label or comment or this will be closed in 10 days."
+          close-issue-message: "This issue was closed because it has been stalled for 10 days with no activity. This does not necessarily mean that the issue is bad, but it most likely means that nobody is willing to take the time to fix it. If you have found Locust useful, then consider contributing a fix yourself!"
+          stale-pr-message: "This PR is stale because it has been open 60 days with no activity. Remove stale label or comment or this will be closed in 10 days."
+          close-pr-message: "This PR was closed because it has been stalled for 10 days with no activity."
+          days-before-close: 10