[BUG][ELIXIR] deserialisation only happens when response has status 200

Created by: mrmstn

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• What's the version of OpenAPI Generator used?
• Have you search for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Bounty to sponsor the fix (example)

Description

Based on the sigature of RequestBuilder.decode, a deserialisation only happens when the statuscode is 200 - no mather of what's defined in the OpenApi Spec

openapi-generator version

• v3.3.4
• v4.0.0-beta2

OpenAPI declaration file content

openapi: 3.0.0
info:
  title: Random Title
  version: 1.0.0
servers:
  - url: https://api.example.com/
paths:
  /create:
    post:
      operationId: createSomething
      responses:
        201:
          description: OK
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Something'

components:
  schemas:
    Something:
      type: object
      properties:
        id:
          type: string
          example: OK

Command line used for generation

docker run --rm -v ${PWD}:/local openapitools/openapi-generator-cli generate \
    -i /local/openapi.yaml \
    -g elixir \
    -o /local/out

Steps to reproduce

Based on the following line, a propper match on the 201 statuscode would be imposible.

https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/elixir/request_builder.ex.mustache#L124

the function createSomething will always return the tesla.env instead of the propper deserialized Something Model

Related issues/PRs

none

Suggest a fix

Add a switch case to the createSomething pipe sequence (in this example...) to determinate the expected module based on the response statuscode, default should be matched with {:ok, %Tesla.Env{}} ->