Resolve uninlined_format_args pedantic clippy lint in test

    warning: variables can be used directly in the `format!` string
      --> tests/trait.rs:32:19
       |
    32 |             .push(format!("dropping {}", self));
       |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
       |
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args
       = note: `-W clippy::uninlined-format-args` implied by `-W clippy::pedantic`
       = help: to override `-W clippy::pedantic` add `#[allow(clippy::uninlined_format_args)]`
    help: change this to
       |
    32 -             .push(format!("dropping {}", self));
    32 +             .push(format!("dropping {self}"));
       |

Author: dtolnay

tests/trait.rs

@@ -26,10 +26,7 @@ impl Display for Log {
 
 impl Drop for Log {
     fn drop(&mut self) {
-        self.events
-            .lock()
-            .unwrap()
-            .push(format!("dropping {}", self));
+        self.events.lock().unwrap().push(format!("dropping {self}"));
     }
 }