add newline

Author: sakria9

clang/test/AST/ast-dump-template-argument-structural-value.cpp

@@ -9,4 +9,4 @@ struct pr126341<{1, 2}>;
 // CHECK-NEXT: ClassTemplateDecl
 // CHECK: Dumping pr126341:
 // CHECK-NEXT: ClassTemplateSpecializationDecl
-// CHECK-NEXT: `-TemplateArgument structural value '1+2i'
+// CHECK-NEXT: `-TemplateArgument structural value '1+2i'