Avoid unused_self clippy pedantic lint in test

    error: unused `self` argument
       --> tests/test_expr.rs:266:25
        |
    266 |         fn consume_self(self) {}
        |                         ^^^^
        |
        = note: `-D clippy::unused-self` implied by `-D clippy::pedantic`
        = help: consider refactoring to a associated function
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unused_self

tests/test_expr.rs

@@ -263,7 +263,9 @@ fn test_top_level_none_delimiter() {
     struct A;
 
     impl A {
-        fn consume_self(self) {}
+        fn consume_self(self) {
+            let _ = self;
+        }
     }
 
     clone!(&A).consume_self();