CI - Enforce Linear issue on pull requests

.github/workflows/require-linear-issue.yml

@@ -0,0 +1,25 @@
+name: Require Linear Issue in Pull Request
+
+on:
+  workflow_dispatch:
+  pull_request:
+    branches:
+      - main
+    types: [opened, reopened]
+
+jobs:
+  require-linear-issue:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Find the Linear Issue
+        id: find-issue
+        uses: ctriolo/action-find-linear-issue@v0.60
+        with:
+          linear-api-key: ${{ secrets.LINEAR_API_KEY }}
+
+      - name: Require Linear Issue
+        run: |
+          if [ -z "${{ steps.find-issue.outputs.linear-issue-identifier }}" ]; then
+            echo "Please add a Linear ID to the title of the Pull Request. Using the Linear branch name would have done this automatically."
+            exit 1
+          fi