ci: move PR validation to separate pipeline

Author: mehalter

.github/workflows/ci.yml

@@ -1,15 +1,23 @@
 name: AstroNvim
 on:
   push:
-    branches: ["main"]
+    branches: [main]
   pull_request:
+  pull_request_target:
+    types: [opened, edited, synchronize]
 
 jobs:
   CI:
     uses: AstroNvim/.github/.github/workflows/plugin_ci.yml@main
+    if: ${{ github.event_name != 'pull_request_target' }}
     secrets: inherit
     with:
       plugin_name: ${{ github.event.repository.name }}
       is_production: ${{ github.event_name == 'push' }}
       commit_msg: false
-      pr_title: true
+  PR:
+    uses: AstroNvim/.github/.github/workflows/validate_pr.yml@main
+    if: ${{ github.event_name == 'pull_request_target' }}
+    secrets: inherit
+    with:
+      conventional_title: true