chore(divan_compat_examples): remove useless linting exception

Author: GuillaumeLagrange

crates/divan_compat/examples/benches/math.rs

@@ -63,7 +63,6 @@ mod fibonacci {
         }
     }
 
-    #[allow(dead_code)]
     trait Map: Default {
         fn get(&self, key: u64) -> Option<u64>;
         fn set(&mut self, key: u64, value: u64);