message: Add missing skip_serialize to charge api paramss
diff: @@ -16,25 +16,25 @@ pub struct ChargeOutcome {
  #[derive(Debug, Default, Deserialize, Serialize)]
  pub struct FraudDetails {
  - pub user_report: Option<String>,
  - pub stripe_report: Option<String>,
  + #[serde(skip_serializing_if = "Option::is_none")] pub user_report: Option<String>,
  + #[serde(skip_serializing_if = "Option::is_none")] pub stripe_report: Option<String>,
  }
  #[derive(Debug, Deserialize, Serialize)]
  pub struct ShippingDetails {
  + pub name: String,
  pub address: Address,
  - pub carrier: Option<String>, // eg. Fedex, UPS, USPS
  - pub name: String, // TODO: Is this possibly null?
  - pub phone: Option<String>,
  - pub tracking_number: Option<String>,
  + #[serde(skip_serializing_if = "Option::is_none")] pub carrier: Option<String>, // eg. Fedex, UPS, USPS
  + #[serde(skip_serializing_if = "Option::is_none")] pub phone: Option<String>,
  + #[serde(skip_serializing_if = "Option::is_none")] pub tracking_number: Option<String>,
  }
  #[derive(Default, Serialize)]
  pub struct CaptureParams<'a> {
  - pub amount: Option<u64>,
  - pub application_fee: Option<u64>,
  - pub receipt_email: Option<&'a str>,
  - pub statement_descriptor: Option<&'a str>,
  + #[serde(skip_serializing_if = "Option::is_none")] pub amount: Option<u64>,
  + #[serde(skip_serializing_if = "Option::is_none")] pub application_fee: Option<u64>,
  + #[serde(skip_serializing_if = "Option::is_none")] pub receipt_email: Option<&'a str>,
  + #[serde(skip_serializing_if = "Option::is_none")] pub statement_descriptor: Option<&'a str>,
  }
  #[derive(Serialize)]
  