fix: code injection via template expansion

https://docs.zizmor.sh/audits/#dangerous-triggers

Author: MaxymVlasov

.github/workflows/pr-title.yml

@@ -1,7 +1,7 @@
 name: Validate PR title
 
 on:
-  pull_request_target:
+  pull_request:
     types:
     - opened
     - edited