readOnly property not marked as optional in the generated model

Describe the bug
Fields marked as readOnly in a schema in the OpenAPI document are not set as optional in the generated model.
This makes them required in the body of any POST request in which this model is used, defeating the purpose of using the readOnly property.

OpenAPI Spec File

openapi: 3.1.0
info:
  title: Minimal bug reproduction API
  version: 1.0.0
paths:
  /bug:
    get:
      summary: Get all bugs
      responses:
        "200":
          description: A list of bugs
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: "#/components/schemas/Bug"
    post:
      summary: Create a bug
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: "#/components/schemas/Bug"
      responses:
        "201":
          description: Bug created
          content:
            application/json:
              schema:
                $ref: "#/components/schemas/Bug"

components:
  schemas:
    Bug:
      type: object
      properties:
        id:
          readOnly: true
          type: integer
        created_at:
          readOnly: true
          type: string
          format: date-time
        name:
          type: string
        description:
          type: string
        status:
          type: string
          enum:
            - open
            - closed
      required:
        - id
        - name
        - description
        - status
        - created_at

Desktop (please complete the following information):

• OS: [Windows 11]
• Python Version: [3.12]
• openapi-python-client version [0.22]

まず、提供された OpenAPI 3.1 の再現ケースを openapi-python-client 0.22 で実行し、生成された Bug モデルと POST の使用方法を調べます。readOnly フィールドと required フィールドがどこで変換されるかを追跡します。readOnly フィールドが POST 入力では必須でなく、一方で生成されたレスポンスモデルでは引き続き利用可能になり、回帰テストのカバレッジが追加されれば完了です。