crypto: Don't borrow inside a format unnecessarily

Co-authored-by: Jonas Platte <jplatte@users.noreply.github.com>

matrix_sdk_crypto/src/store/memorystore.rs

@@ -39,7 +39,7 @@ use crate::{
 fn encode_key_info(info: &RequestedKeyInfo) -> String {
     format!(
         "{}{}{}{}",
-        &info.room_id, &info.sender_key, &info.algorithm, &info.session_id
+        info.room_id, info.sender_key, info.algorithm, info.session_id
     )
 }