fix: update axum generated multipart requests to own the Multipart or Body

Notes: &Multipart cannot access fields, as we need mutable access.

Author: AlexandreCassagne

modules/openapi-generator/src/main/resources/rust-axum/apis.mustache

@@ -68,10 +68,10 @@ pub trait {{classnamePascalCase}}<E: std::fmt::Debug + Send + Sync + 'static = (
     {{/x-consumes-multipart}}
     {{/x-consumes-multipart-related}}
     {{#x-consumes-multipart}}
-        body: &Multipart,
+    body: Multipart,
     {{/x-consumes-multipart}}
     {{#x-consumes-multipart-related}}
-        body: &axum::body::Body,
+    body: axum::body::Body,
     {{/x-consumes-multipart-related}}
     ) -> Result<{{{operationId}}}Response, E>;
   {{/vendorExtensions}}