Run workflow for pull requests

Author: botder

.github/workflows/validate.yaml

@@ -3,10 +3,14 @@ name: YAML validation
 on:
   push:
     paths:
-      - 'elements/**/*.yaml'
+      - &files 'elements/**/*.yaml'
       - 'events/**/*.yaml'
       - 'functions/**/*.yaml'
       - 'schemas/**/*.yaml'
+  pull_request:
+    paths:
+      - *files
+  workflow_dispatch:
 
 jobs:
   validate: