[BUG] No bearer header causes crash in async authenticate() HttpBearer

[mmkhitaryan]

Describe the bug
I expect that if I write the same authenticate handlers in async and sync, they behave the same. But in reality, I get proper 401 with SyncBearerAuth and crash for AsyncBearerAuth with the same handling logic.

Traceback (most recent call last):
  File "C:\Users\Marat\Desktop\csmbackend\.venv\Lib\site-packages\ninja\operation.py", line 190, in _run_authentication
    result = async_to_sync(callback)(request)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Marat\Desktop\csmbackend\.venv\Lib\site-packages\asgiref\sync.py", line 254, in __call__
    return call_result.result()
           ^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Marat\AppData\Local\Programs\Python\Python312\Lib\concurrent\futures\_base.py", line 449, in result
    return self.__get_result()
           ^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Marat\AppData\Local\Programs\Python\Python312\Lib\concurrent\futures\_base.py", line 401, in __get_result
    raise self._exception
  File "C:\Users\Marat\Desktop\csmbackend\.venv\Lib\site-packages\asgiref\sync.py", line 331, in main_wrap
    result = await self.awaitable(*args, **kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: object NoneType can't be used in 'await' expression

Versions (please complete the following information):

• Python version: 3.12.8
• Django version: 5.1.4
• Django-Ninja version: 1.3.0
• Pydantic version: 2.10.5

Note you can quickly get this by runninng in ./manage.py shell this line:

import pytest

from ninja.security import (
    HttpBearer,
)
from ninja import NinjaAPI
from ninja.testing import TestClient, TestAsyncClient

class SyncBearerAuth(HttpBearer):
    def authenticate(self, request, token: str):
        return

class AsyncBearerAuth(HttpBearer):
    async def authenticate(self, request, token: str):
        return

api = NinjaAPI()

@api.get("/sync/", auth=SyncBearerAuth())
def sync_auth(request):
    return

@api.get("/async/", auth=AsyncBearerAuth())
def async_auth(request):
    return

client = TestClient(api)
async_client = TestAsyncClient(api)

def test_async_bearer_invalid_bearer():
    response = client.get("/async/", headers={"Authorization": "Bearer 123"})
    assert response.status_code == 401

def test_async_bearer_no_bearer():
    # TypeError: object NoneType can't be used in 'await' expression
    response = client.get("/async/")
    assert response.status_code == 401

def test_sync_bearer_no_berer():
    response = client.get("/sync/")
    assert response.status_code == 401

As you can see, the authenticate implementations are the same but no bearer header causes different behavior:

FAILED tests/test_weird_case.py::test_bearer_auth - TypeError: object NoneType can't be used in 'await' expression

[mmkhitaryan]

Made a PR: #1387