python: Refactor models to use alias_generator (#1678)

```json
{
  "file-generated-at": "2025-01-30T21:03:44.929377827+00:00",
  "git-rev": "f56cc1dced773360bae301cac14d84029ac0f2e7",
  "openapi-codegen-version": "0.1.0",
  "openapi.json-sha256": "27c305c4c890291e9dd2506cebe18422317faea9963f3d9abf89a405731e3206"
}
```

Note, the field `to_modify` on
[this](https://github.com/svix/svix-webhooks-private/blob/dec537950635d73531734c2980811163191c4d32/rust/src/models/event_type_import_open_api_out_data.rs#L7)
model does not follow camelCasing

Author: svix-mman

python/mypy.ini

@@ -1,3 +1,2 @@
 [mypy]
 strict = True
-plugins = pydantic.mypy

python/svix/models/aggregate_event_types_out.py

@@ -2,10 +2,10 @@
 
 from .background_task_status import BackgroundTaskStatus
 from .background_task_type import BackgroundTaskType
-from .common import SvixBaseModel
+from .common import BaseModel
 
 
-class AggregateEventTypesOut(SvixBaseModel):
+class AggregateEventTypesOut(BaseModel):
     id: str
 
     status: BackgroundTaskStatus