message: fix(s2n-quic): remove &mut from datagram_mut
diff: @@ -389,7 +389,7 @@ macro_rules! impl_handle_api {
  /// );
  /// ```
  pub fn datagram_mut<Query, ProviderType, Outcome>(
  - &mut self,
  + &self,
  query: Query,
  ) -> core::result::Result<Outcome, s2n_quic_core::query::Error>
  where
  