chore: disable pull requests

Author: dessant

.github/pull_request_template.md

@@ -0,0 +1 @@
+This project does not accept pull requests. Please use issues to report bugs or suggest new features.

.github/workflows/lockdown.yml

@@ -0,0 +1,18 @@
+name: 'Repo Lockdown'
+
+on:
+  pull_request_target:
+    types: opened
+
+permissions:
+  pull-requests: write
+
+jobs:
+  action:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: dessant/repo-lockdown@v2
+        with:
+          exclude-pr-created-before: '2021-11-02T00:00:00Z'
+          pr-comment: 'This project does not accept pull requests. Please use issues to report bugs or suggest new features.'
+          process-only: 'prs'