Suppress deprecation warning on mem::uninitialized

serde/src/ser/impls.rs

@@ -620,6 +620,7 @@ impl Serialize for SystemTime {
 #[cfg(feature = "std")]
 macro_rules! serialize_display_bounded_length {
     ($value:expr, $max:expr, $serializer:expr) => {{
+        #[allow(deprecated)]
         let mut buffer: [u8; $max] = unsafe { mem::uninitialized() };
         let remaining_len = {
             let mut remaining = &mut buffer[..];