Remove some AsRef<str> (#3354)

Using &str instead of AsRef is better for compile times, binary size and code complexity.

src/dc_receive_imf.rs

@@ -2008,7 +2008,7 @@ async fn check_verified_properties(
     let rows = context
         .sql
         .query_map(
-            format!(
+            &format!(
                 "SELECT c.addr, LENGTH(ps.verified_key_fingerprint)  FROM contacts c  \
              LEFT JOIN acpeerstates ps ON c.addr=ps.addr  WHERE c.id IN({}) ",
                 sql::repeat_vars(to_ids.len())