Add basic model tests

funkwhale_api_client/models/metadata.py

-from typing import Any, Dict, List, Type, TypeVar, cast
+from typing import Any, Dict, List, Type, TypeVar, Union, cast
 
 import attr
 
@@ -6,6 +6,7 @@ from ..models.allow_list_stat import AllowListStat
 from ..models.endpoints import Endpoints
 from ..models.metadata_usage import MetadataUsage
 from ..models.report_type import ReportType
+from ..types import UNSET, Unset
 
 T = TypeVar("T", bound="Metadata")
 
@@ -31,7 +32,7 @@ class Metadata:
         funkwhale_support_message_enabled (bool):
         instance_support_message (str):
         endpoints (Endpoints):
-        usage (MetadataUsage):
+        usage (Union[Unset, MetadataUsage]):
     """
 
     actor_id: str
@@ -51,7 +52,7 @@ class Metadata:
     funkwhale_support_message_enabled: bool
     instance_support_message: str
     endpoints: Endpoints
-    usage: MetadataUsage
+    usage: Union[Unset, MetadataUsage] = UNSET
     additional_properties: Dict[str, Any] = attr.ib(init=False, factory=dict)
 
     def to_dict(self) -> Dict[str, Any]:
@@ -80,7 +81,9 @@ class Metadata:
         instance_support_message = self.instance_support_message
         endpoints = self.endpoints.to_dict()
 
-        usage = self.usage.to_dict()
+        usage: Union[Unset, Dict[str, Any]] = UNSET
+        if not isinstance(self.usage, Unset):
+            usage = self.usage.to_dict()
 
         field_dict: Dict[str, Any] = {}
         field_dict.update(self.additional_properties)
@@ -103,9 +106,10 @@ class Metadata:
                 "funkwhaleSupportMessageEnabled": funkwhale_support_message_enabled,
                 "instanceSupportMessage": instance_support_message,
                 "endpoints": endpoints,
-                "usage": usage,
             }
         )
+        if usage is not UNSET:
+            field_dict["usage"] = usage
 
         return field_dict
 
@@ -151,7 +155,12 @@ class Metadata:
 
         endpoints = Endpoints.from_dict(d.pop("endpoints"))
 
-        usage = MetadataUsage.from_dict(d.pop("usage"))
+        _usage = d.pop("usage", UNSET)
+        usage: Union[Unset, MetadataUsage]
+        if isinstance(_usage, Unset):
+            usage = UNSET
+        else:
+            usage = MetadataUsage.from_dict(_usage)
 
         metadata = cls(
             actor_id=actor_id,