[Rust] Use upper came case for enum options

Fixes this warning:
warning: variant `shipped` should have an upper camel case name
  --> reqwest/petstore/src/models/order.rs:53:5
   |
53 |     shipped,
   |     ^^^^^^^ help: convert the identifier to upper camel case (notice the capitalization): `Shipped`
   |
   = note: `#[warn(non_camel_case_types)]` (part of `#[warn(nonstandard_style)]`) on by default

Author: adi-code

samples/client/petstore/rust/reqwest/petstore/src/models/order.rs

@@ -50,7 +50,7 @@ pub enum Status {
     #[serde(rename = "approved")]
     Approved,
     #[serde(rename = "delivered")]
-    shipped,
+    Shipped,
 }
 
 impl Default for Status {