Can not upload binary data from python client generated by swagger

Code generated for POST binary code fails with error:

Cannot prepare a request message for provided
                             arguments. Please check that your arguments match
                             declared content type.

Specification example:

openapi: 3.0.3
info:
  title: Tasks Example
  version: 0.0.1
tags:
  - name: example
    description: Example spec
paths:
  /task/{task_id}/attachment:
    post:
      summary: Add attachment for the task
      description: Add binary attachemnt for te task provided by task id
      operationId: task_attachment_post
      tags:
        - tasks
      parameters:
        - $ref: '#/components/parameters/task_id'
      requestBody:
        description: Binary attachment format
        required: true
        content:
          application/octet-stream:
            schema:
              type: string
              format: binary
      responses:
        201:
          description: Nothing (void)
components:
  parameters:
    task_id:
      name: task_id
      in: path
      schema:
        type: integer
      required: true
      description: Id of the tile
      example: 1234

config (just for case):

{
  "generateSourceCodeOnly": true,
  "packageName": "tasks_example",
  "projectName": "tasks example",
  "packageVersion": "0.0.1"
}

generate:

docker run -it --rm -v ${PWD}:/app -w /app swaggerapi/swagger-codegen-cli-v3:3.0.24 generate --input-spec /app/spec.yml --lang python  --config /app/config.json --output /app/

my client code:

import random
import secrets

from tasks_example import TasksApi


if __name__ == "__main__":
    file_len = random.randint(1000, 10000)
    body_bytes = secrets.token_bytes(file_len)
    task_api = TasksApi()
    task_api.task_attachment_post(body_bytes, 123)

run my app:

pip install -r requirements.txt
python -m task_client_example

got error:

Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/runpy.py", line 194, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "/Users/risik/work/task_example/task_client_example.py", line 11, in <module>
    task_api.task_attachment_post(body_bytes, 123)
  File "/Users/risik/work/task_example/tasks_example/api/tasks_api.py", line 55, in task_attachment_post
    (data) = self.task_attachment_post_with_http_info(body, task_id, **kwargs)  # noqa: E501
  File "/Users/risik/work/task_example/tasks_example/api/tasks_api.py", line 122, in task_attachment_post_with_http_info
    return self.api_client.call_api(
  File "/Users/risik/work/task_example/tasks_example/api_client.py", line 316, in call_api
    return self.__call_api(resource_path, method,
  File "/Users/risik/work/task_example/tasks_example/api_client.py", line 148, in __call_api
    response_data = self.request(
  File "/Users/risik/work/task_example/tasks_example/api_client.py", line 358, in request
    return self.rest_client.POST(url,
  File "/Users/risik/work/task_example/tasks_example/rest.py", line 268, in POST
    return self.request("POST", url,
  File "/Users/risik/work/task_example/tasks_example/rest.py", line 203, in request
    raise ApiException(status=0, reason=msg)
tasks_example.rest.ApiException: (0)
Reason: Cannot prepare a request message for provided
                             arguments. Please check that your arguments match
                             declared content type.

Reproduce the failure with spec.yml using the documented swagger-codegen-cli Docker command, then trace the generated call through tasks_example/api/tasks_api.py, api_client.py, and rest.py. Check the binary POST request path and verify that the generated client can send the supplied bytes without raising ApiException.