Add a PR closer

Currently, it's impossible to disable pull request on github, so we have
to add a workflow event to trigger it, which will automatically close
the PR when attempting to open/reopen a PR on the github repo, and send a
reminder on how to contribute patches to the crash-utility mailing list.

Signed-off-by: Lianbo Jiang <[email protected]>
Signed-off-by: Tao Liu <[email protected]>

Author: lian-bo

.github/workflows/pr-closer.yml

@@ -0,0 +1,13 @@
+name: Close Pull Request
+
+on:
+  pull_request_target:
+    types: [opened, reopened]
+
+jobs:
+  run:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: superbrothers/close-pull-request@v3
+      with:
+        comment: "The github repo does not accept PRs, please subscribe to mail list via https://lists.crash-utility.osci.io/admin/lists/devel.lists.crash-utility.osci.io/ for contribution and discussion. Or post your patch to mail list: [email protected]"