Add workflow for "/keep-open" commands

Signed-off-by: Russell Bryant <[email protected]>

.github/workflows/keep-open.yml

@@ -0,0 +1,22 @@
+name: Keep Open Labeler
+on:
+  issue_comment:
+    types: [created]
+
+jobs:
+  add-keep-open-label:
+    runs-on: ubuntu-latest
+    if: |
+      contains(github.event.comment.body, '/keep-open') ||
+      contains(github.event.comment.body, '/keep_open') ||
+      contains(github.event.comment.body, '/keepopen')
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@eef61447b9ff4aafe5dcd4e0bbf5d482be7e7871 # v4.2.1
+
+      - name: Add "keep-open" label
+        uses: actions-ecosystem/action-add-labels@bd52874380e3909a1ac983768df6976535ece7f8 # v1.1.3
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          labels: keep-open
+          issue_number: ${{ github.event.issue.number || github.event.pull_request.number }}