issues: new issue workflow

Adding a new workflow per https://docs.github.com/en/actions/managing-issues-and-pull-requests/closing-inactive-issues to help us manage stale and inactive issues.

In this first iteration, we'll focus on issues with the "help wanted" label. Issues with no activity after 60 days will be marked stale, then closed 90 days later.

.github/workflows/ISSUE_WORKFLOW.yaml

@@ -0,0 +1,22 @@
+name: Close inactive issues
+on:
+  schedule:
+    - cron: "30 1 * * *"
+
+jobs:
+  close-issues:
+    runs-on: ubuntu-latest
+    permissions:
+      issues: write
+      pull-requests: write
+    steps:
+      - uses: actions/stale@v5
+        with:
+          days-before-issue-stale: 60
+          days-before-issue-close: 90
+          any-of-labels: help wanted
+          stale-issue-label: "stale"
+          stale-issue-message: "This issue is stale because it has been open for 60 days with no activity."
+          close-issue-message: "This issue was closed because it has been inactive for 90 days since being marked as stale."
+          days-before-pr-stale: -1
+          days-before-pr-close: -1