make OrderInfo use Option<String> instead of String

src/types/order_info.rs

@@ -8,14 +8,14 @@ use crate::types::ShippingAddress;
 #[derive(Clone, Debug, Eq, Hash, PartialEq, Serialize, Deserialize)]
 pub struct OrderInfo {
     /// User's name.
-    pub name: String,
+    pub name: Option<String>,
 
     /// User's phone number.
-    pub phone_number: String,
+    pub phone_number: Option<String>,
 
     /// User's email.
-    pub email: String,
+    pub email: Option<String>,
 
     /// User's shipping address.
-    pub shipping_address: ShippingAddress,
+    pub shipping_address: Option<ShippingAddress>,
 }

src/types/pre_checkout_query.rs

@@ -35,5 +35,5 @@ pub struct PreCheckoutQuery {
     pub shipping_option_id: Option<String>,
 
     /// Order info provided by the user.
-    pub order_info: Option<OrderInfo>,
+    pub order_info: OrderInfo,
 }