v0.8.21

• Implement skip_serializing for enum variants (#653, thanks @shinglyu)

  #[derive(Serialize)]
  enum E {
      A(bool),
      B(String),
      #[serde(skip_serializing)]
      C(NotSerializable),
  }

  Serialization will fail with a message if that particular variant is the one being serialized.

  "The enum variant E::C cannot be serialized"