Add unit tests for authentication and webhook parsing

- Implement tests for basic and bearer authentication headers in `test_auth.py`.
- Create tests for the `EasybillWebhookParser` in `test_webhooks.py`, covering JSON and form-encoded payloads, as well as a generic parse and acknowledgement method.

generated/sync/docs/FileFormatConfig.md

@@ -0,0 +1,29 @@
+# FileFormatConfig
+
+
+## Properties
+
+Name | Type | Description | Notes
+------------ | ------------- | ------------- | -------------
+**type** | **str** |  | 
+
+## Example
+
+```python
+from easybill_generated_sync.models.file_format_config import FileFormatConfig
+
+# TODO update the JSON string below
+json = "{}"
+# create an instance of FileFormatConfig from a JSON string
+file_format_config_instance = FileFormatConfig.from_json(json)
+# print the JSON string representation of the object
+print(FileFormatConfig.to_json())
+
+# convert the object into a dict
+file_format_config_dict = file_format_config_instance.to_dict()
+# create an instance of FileFormatConfig from a dict
+file_format_config_from_dict = FileFormatConfig.from_dict(file_format_config_dict)
+```
+[[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
+
+