message: Make StringValueLike have Serialize
  Summary: Available on both, so forward it.
diff: @@ -26,6 +26,7 @@ use gazebo::{
  prelude::*,
  };
  use indexmap::Equivalent;
  +use serde::Serialize;
  use crate::{
  collections::{BorrowHashed, Hashed},
  @@ -128,6 +129,7 @@ pub trait StringValueLike<'v>:
  + Copy
  + Clone
  + Dupe
  + + Serialize
  {
  /// Convert to a [`StringValue`].
  fn to_string_value(self) -> StringValue<'v>;
  