ci: close stale issues and PRs

This change adds a github action in order to warn users after 30 days of
inactivity that their PRs and issues are subject to being closed if they
are not updated within the next 5 days. Labels are added to auto-closed
issues so that analysis is easier, and issues with the labels bug or issue
are skipped from this.

I chose not to do this for the enhancement type issues, as the longer term
product backlog is being tracked in Tiaga, not GitHub Issues. Users are
still welcome to log issues for enhancements, but this will encourage them
to keep these discussions alive and work to a conclusion rather than having
the longer-term roadmap split across two places.

Signed-off-by: Ryan Turner <ryan@turnrye.com>

.github/workflows/close-stale.yml

@@ -0,0 +1,20 @@
+name: 'Close stale issues and PRs'
+on:
+  schedule:
+    - cron: '30 1 * * *'
+
+jobs:
+  stale:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/stale@v10
+        with:
+          stale-issue-message: 'This issue is stale because it has been open 30 days with no activity. Please comment within 15 days if this in fact is not stale, otherwise this will be closed.'
+          stale-pr-message: 'This PR is stale because it has been open 30 days with no activity. Please comment within 15 days if this in fact is not stale, otherwise this will be closed.'
+          close-issue-message: 'This issue was closed due to continued inactivity.'
+          close-pr-message: 'This PR was closed due to continued inactivity.'
+          close-issue-label: Stale-Closed
+          close-pr-label: Stale-Closed
+          exempt-issue-labels: bug,issue
+          days-before-stale: 30
+          days-before-close: 15