Update validate.yml

Signed-off-by: Ashley <73482956+ascopes@users.noreply.github.com>

Author: ascopes

.github/workflows/validate.yml

@@ -3,8 +3,9 @@ name: Validate configuration
 on:
   push:
     branches: [ "main" ]
-  pull_request:
-    branches: [ "**" ]
+  pull_request_target:
+    branches:
+      - main
   workflow_call: {}
   workflow_dispatch: {}