fix: AstNode.getATriggerEvent()

getATriggerEvent did not work for nodes outside a Job.
If there is no enclosing job, get the trigger from the enclosing
workflow

ql/lib/codeql/actions/ast/internal/Ast.qll

@@ -114,7 +114,11 @@ abstract class AstNodeImpl extends TAstNode {
   /**
    * Gets and Event triggering this node.
    */
-  EventImpl getATriggerEvent() { result = this.getEnclosingJob().getATriggerEvent() }
+  EventImpl getATriggerEvent() {
+    result = this.getEnclosingJob().getATriggerEvent()
+    or
+    not exists(this.getEnclosingJob()) and result = this.getEnclosingWorkflow().getATriggerEvent()
+  }
 
   /**
    * Gets the enclosing Step.