chore: Prevent PRs targetting the master branch

.github/workflows/pr-base-enforcement.yml

@@ -0,0 +1,19 @@
+name: Prevent PRs targetting master
+
+on:
+  pull_request:
+    branches:
+      - master
+
+jobs:
+  prevent-pr-targetting-master:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Post comment to update base branch
+        run: gh pr comment ${{ github.event.pull_request.number }} --body "⚠️ Pull requests targetting the `master` branch are not allowed. Please update the base branch to `next`."
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      - name: Close PR
+        run: gh pr close ${{ github.event.pull_request.number }} --repo ${{ github.repository }}
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}