fix(ics-23): Auto-derive serde::Serialize for CommitmentPrefix (informalsystems#1230)

* Auto-derive serde::Serialize for CommitmentPrefix

* Add changelog entry

Author: seanchen1991

.changelog/unreleased/breaking-changes/1229-auto-derive-ser-commitment-prefix.md

@@ -0,0 +1,2 @@
+- [ics23] Auto-derive `serde::Serialize` for `CommitmentPrefix`.
+  ([\#1229](https://github.com/cosmos/ibc-rs/issues/1229))

ibc-core/ics23-commitment/types/src/commitment.rs

@@ -141,7 +141,7 @@ impl<'a> TryFrom<&'a CommitmentProofBytes> for MerkleProof {
     feature = "borsh",
     derive(borsh::BorshSerialize, borsh::BorshDeserialize)
 )]
-#[cfg_attr(feature = "serde", derive(serde::Deserialize))]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
 #[cfg_attr(feature = "schema", derive(schemars::JsonSchema))]
 #[derive(Clone, PartialEq, Eq, Hash)]
 pub struct CommitmentPrefix {
@@ -183,13 +183,3 @@ impl fmt::Debug for CommitmentPrefix {
         }
     }
 }
-
-#[cfg(feature = "serde")]
-impl serde::Serialize for CommitmentPrefix {
-    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    where
-        S: serde::Serializer,
-    {
-        format!("{self:?}").serialize(serializer)
-    }
-}