Fix query param array with reference

[villain-b]

Summary

This commit fixes an error in the codegen for API request param defined as array which references another schema object. The generated code to parse an individual array item used the argument type (Vec<TheType>) so the generated code didn't compile (trying to p.parse::<Vec<TheType>>() instead of p.parse::<TheType>()).

Tests

I'm using the following OpenAPI definition:

components:
  schemas:
    OrderState:
      type: string
      enum:
        - CREATED
[...]
paths:
  /some:
    get:
      operationId: getOrders
      parameters:
[...]
        - name: states
          in: query
          schema:
            type: array
            items:
              $ref: '#/components/schemas/OrderState'
[...]

I would expect it to generate correct Rust code that can parse the OrderState string into an enum (it works for request body and responses).

Without the change

I'm getting the following compilation error:

error[E0277]: the trait bound `Vec<OrderState>: FromStr` is not satisfied
     |
     |                         p.parse::<Vec<crate::models::OrderState>>()
     |                           ^^^^^ the trait `FromStr` is not implemented for `Vec<OrderState>`

With the change

Code compiles.