Avoid Unstable Sort (#12455)

* dont use unstable sort

* remove comment

* add clippy rule

substrate/frame/contracts/src/wasm/runtime.rs

@@ -1976,11 +1976,7 @@ pub mod env {
 		data_len: u32,
 	) -> Result<(), TrapReason> {
 		fn has_duplicates<T: Ord>(items: &mut Vec<T>) -> bool {
-			// # Warning
-			//
-			// Unstable sorts are non-deterministic across architectures. The usage here is OK
-			// because we are rejecting duplicates which removes the non determinism.
-			items.sort_unstable();
+			items.sort();
 			// Find any two consecutive equal elements.
 			items.windows(2).any(|w| match &w {
 				&[a, b] => a == b,