Object has no attribute 'get_all' when calling calendar.get_schedule.post()

I'm currently trying to get a room schedule through this code:

credential = ClientSecretCredential(
    config['tenantID'],
    config['clientID'],
    config['clientSecret']
)
scopes = ['https://graph.microsoft.com/.default']
client = GraphServiceClient(credentials=credential, scopes=scopes)

# GET /users/{id | userPrincipalName}
async def get_rooms():
    
    request_body = GetSchedulePostRequestBody(
        schedules = [
            "StanzaA@qq7h.onmicrosoft.com"
        ],
        start_time = DateTimeTimeZone(
            date_time = "2023-03-15T09:00:00",
            time_zone = "Pacific Standard Time",
        ),
        end_time = DateTimeTimeZone(
            date_time = "2023-12-15T18:00:00",
            time_zone = "Pacific Standard Time",
        ),
        availability_view_interval = 60,
    )

    request_configuration = GetScheduleRequestBuilder.GetScheduleRequestBuilderPostRequestConfiguration(
    headers = {
            'Prefer' : "outlook.timezone=\"Pacific Standard Time\"",
    }

    )

    result = await client.me.calendar.get_schedule.post(request_body, request_configuration = request_configuration)


    if result:
        print(result.value)

asyncio.run(get_rooms())

But when running I get an error coming from kiota

Traceback (most recent call last):
  File "C:\Users\Massimo Mendozza\Documents\GitHub\DynamicsToJoan\main.py", line 52, in <module>
    asyncio.run(get_rooms())
  File "C:\Users\Massimo Mendozza\AppData\Local\Programs\Python\Python311\Lib\asyncio\runners.py", line 190, in run
    return runner.run(main)
           ^^^^^^^^^^^^^^^^
  File "C:\Users\Massimo Mendozza\AppData\Local\Programs\Python\Python311\Lib\asyncio\runners.py", line 118, in run
    return self._loop.run_until_complete(task)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Massimo Mendozza\AppData\Local\Programs\Python\Python311\Lib\asyncio\base_events.py", line 650, in run_until_complete
    return future.result()
           ^^^^^^^^^^^^^^^
  File "C:\Users\Massimo Mendozza\Documents\GitHub\DynamicsToJoan\main.py", line 46, in get_rooms
    result = await client.me.calendar.get_schedule.post(request_body, request_configuration = request_configuration)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Massimo Mendozza\Documents\GitHub\DynamicsToJoan\Lib\site-packages\msgraph\generated\users\item\calendar\get_schedule\get_schedule_request_builder.py", line 40, in post
    request_info = self.to_post_request_information(
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Massimo Mendozza\Documents\GitHub\DynamicsToJoan\Lib\site-packages\msgraph\generated\users\item\calendar\get_schedule\get_schedule_request_builder.py", line 66, in to_post_request_information        
    request_info.headers.add_all(request_configuration.headers)
  File "C:\Users\Massimo Mendozza\Documents\GitHub\DynamicsToJoan\Lib\site-packages\kiota_abstractions\headers_collection.py", line 83, in add_all
    for key, values in headers.get_all().items():
                       ^^^^^^^^^^^^^^^
AttributeError: 'dict' object has no attribute 'get_all'

I'm currently running under this pyvenv:

home = C:\Users\Massimo Mendozza\AppData\Local\Programs\Python\Python311
include-system-site-packages = false
version = 3.11.0
executable = C:\Users\Massimo Mendozza\AppData\Local\Programs\Python\Python311\python.exe
command = C:\Users\Massimo Mendozza\AppData\Local\Programs\Python\Python311\python.exe -m venv C:\Users\Massimo Mendozza\Documents\GitHub\DynamicsToJoan

And this are my packages version:

Package                              Version
------------------------------------ ---------
aiohttp                              3.8.6
aiosignal                            1.3.1
anyio                                4.0.0
async-timeout                        4.0.3
attrs                                23.1.0
azure-core                           1.29.5
azure-identity                       1.15.0
certifi                              2023.7.22
cffi                                 1.16.0
charset-normalizer                   3.3.2
cryptography                         41.0.5
Deprecated                           1.2.14
frozenlist                           1.4.0
h11                                  0.14.0
h2                                   4.1.0
hpack                                4.0.0
httpcore                             0.18.0
httpx                                0.25.0
hyperframe                           6.0.1
idna                                 3.4
importlib-metadata                   6.8.0
microsoft-kiota-abstractions         1.0.0
microsoft-kiota-authentication-azure 1.0.0
microsoft-kiota-http                 1.0.0
microsoft-kiota-serialization-json   1.0.0
microsoft-kiota-serialization-text   1.0.0
msal                                 1.24.1
msal-extensions                      1.0.0
msgraph-core                         1.0.0a4
msgraph-sdk                          1.0.0
multidict                            6.0.4
opentelemetry-api                    1.20.0
opentelemetry-sdk                    1.20.0
opentelemetry-semantic-conventions   0.41b0
pendulum                             2.1.2
pip                                  22.3
portalocker                          2.8.2
pycparser                            2.21
PyJWT                                2.8.0
python-dateutil                      2.8.2
python-dotenv                        1.0.0
pytzdata                             2020.1
pywin32                              306
requests                             2.31.0
setuptools                           65.5.0
six                                  1.16.0
sniffio                              1.3.0
std-uritemplate                      0.0.46
typing_extensions                    4.8.0
urllib3                              2.0.7
wrapt                                1.15.0
yarl                                 1.9.2
zipp                                 3.17.0

Start with the request configuration and headers handling in the traceback's generated get_schedule_request_builder.py, then read kiota_abstractions/headers_collection.py where get_all() is called. Check what header type the request configuration expects and compare it with the dict used in the example. Done means the reported request no longer fails at headers.add_all and the expected header behavior is verified.