fix remaining clippy error

Author: JeelRajodiya

datafusion/spark/src/function/string/encode.rs

@@ -551,7 +551,7 @@ mod tests {
     fn hex_encode(bytes: &[u8]) -> String {
         bytes
             .iter()
-            .map(|b| format!("{:02X}", b))
+            .map(|b| format!("{b:02X}"))
             .collect::<String>()
     }
 }