[BUG] Python generator incorrectly renames valid model names

Description

The generator is renaming valid model object names. Looking at https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PythonClientCodegen.java#L119 it seems that it is ignoring casing which means that valid names such as Property are being renamed to ModelProperty

openapi-generator version

4.1.0-SNAPSHOT

OpenAPI declaration file content or url

swagger: "2.0"
info:
  description: "API description"
  version: "1.0.0"
  title: "Demo API"
  license:
    name: "Apache 2.0"
    url: "http://www.apache.org/licenses/LICENSE-2.0.html"
host: "host.com"
basePath: "/v2"
tags:
- name: "myapi"
  description: "do something"

schemes:
- "https"
- "http"
paths:
  /myroute:
    post:
      tags:
      - "myapi"
      summary: "add something"
      description: ""
      operationId: "addSomthing"
      consumes:
      - "application/json"
      produces:
      - "application/json"
      parameters:
      - in: "body"
        name: "body"
        description: "Do Something"
        required: true
        schema:
          $ref: "#/definitions/Property"
      responses:
        405:
          description: "Invalid input"

definitions:
  Property:
    type: "object"
    properties:
      id:
        type: "integer"
        format: "int64"

Command line used for generation

$ docker run --rm -v ${PWD}:/local openapitools/openapi-generator-cli generate -i /local/example.yml -g python -o /local/out/sdk

Suggest a fix

Preserve casing when checking for keywords

Start in modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PythonClientCodegen.java around line 119, then reproduce the issue with the provided OpenAPI declaration and Docker command. Done means valid model names such as Property retain their casing and are not renamed to ModelProperty.