set_container_access_policy returns 400 Bad Request on a valid request

### Which service(blob, file, queue, table) does this issue concern?
blob
### Which version of the Azurite was used?
3.29.0
### Where do you get Azurite? (npm, DockerHub, NuGet, Visual Studio Code Extension)
DockerHub
### What's the Node.js version?
--
### What problem was encountered?
API set_container_access_policy returns with 400 Bad Request on a valid request. The same request succeeds with Azure (Requests were made using the Python SDK).
### Steps to reproduce the issue?
The following code should reproduce it
```
from azure.storage.blob import BlobServiceClient
from azure.storage.blob import PublicAccess
from azure.storage.blob import AccessPolicy

blob_service_client = BlobServiceClient.from_connection_string(f'{conn_string}')
container_client = blob_service_client.get_container_client('container')

container_client.create_container()
container_client.set_container_access_policy(signed_identifiers={'test': AccessPolicy()}, public_access=PublicAccess.Container)
```
>azure.core.exceptions.HttpResponseError: Bad Request
ErrorCode:None

If possible, please provide the debug log using the -d parameter, replacing \ with an appropriate path for your OS, or review the instructions for docker containers:

```
-d ""
```

Please be sure to remove any PII or sensitive information before sharing!
The debug log will log raw request headers and bodies, so that we can replay these against Azurite using REST and create tests to validate resolution.

### Have you found a mitigation/solution?