Use Pin<Box<>> for collation future (#1792)

polkadot/node/overseer/src/lib.rs

@@ -1876,7 +1876,7 @@ mod tests {
 	fn test_collator_generation_msg() -> CollationGenerationMessage {
 		CollationGenerationMessage::Initialize(CollationGenerationConfig {
 			key: CollatorPair::generate().0,
-			collator: Box::new(|_, _| Box::new(TestCollator)),
+			collator: Box::new(|_, _| TestCollator.boxed()),
 			para_id: Default::default(),
 		})
 	}