Create stale.yml

Adding this check for this repo to clean up old issues if they are no longer relevant by adding 'stale' label. Copied this from another repo that uses this same process.

Author: shcorbett

.github/workflows/stale.yml

@@ -0,0 +1,25 @@
+
+name: Mark stale issues and pull requests
+
+on:
+  schedule:
+  - cron: "0 0 * * *"
+
+jobs:
+  stale:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/stale@v3
+      with:
+        repo-token: ${{ secrets.GITHUB_TOKEN }}
+        stale-issue-message: "👋 This issue has been marked as stale because it has been open with no activity. You can: comment on the issue or remove the stale label to hold stale off for a while, add the `Keep` label to hold stale off permanently, or do nothing. If you do nothing this issue will be closed eventually by the stale bot."
+        stale-issue-label: "Stale"
+        exempt-issue-labels: "Keep"
+        stale-pr-message: "👋 This pull request has been marked as stale because it has been open with no activity. You can: comment on the issue or remove the stale label to hold stale off for a while, add the `Keep` label to hold stale off permanently, or do nothing. If you do nothing this pull request will be closed eventually by the stale bot."
+        stale-pr-label: "Stale"
+        exempt-pr-labels: "Keep, epic, initiative, GHAE"
+        days-before-stale: 30 # 1 month, which accounts for "now" and "next", but anything beyond is "never"
+        days-before-close: 5
+        ascending: true