fix linter errors

pyserve/asgi_mount.py

@@ -17,7 +17,7 @@ logger = get_logger(__name__)
 
 
 class ASGIAppLoader:
-    def __init__(self):
+    def __init__(self) -> None:
         self._apps: Dict[str, ASGIApp] = {}
         self._wsgi_adapters: Dict[str, ASGIApp] = {}
 
@@ -59,7 +59,7 @@ class ASGIAppLoader:
                 logger.info(f"Wrapped WSGI app: {app_path}")
 
             self._apps[app_path] = app
-            return app
+            return cast(ASGIApp, app)
 
         except ImportError as e:
             logger.error(f"Failed to import application {app_path}: {e}")
@@ -137,7 +137,7 @@ class MountedApp:
 
 
 class ASGIMountManager:
-    def __init__(self):
+    def __init__(self) -> None:
         self._mounts: list[MountedApp] = []
         self._loader = ASGIAppLoader()
 
@@ -288,8 +288,8 @@ def create_django_app(
     os.environ.setdefault("DJANGO_SETTINGS_MODULE", settings_module)
 
     try:
-        from django.core.asgi import get_asgi_application
-        return get_asgi_application()
+        from django.core.asgi import get_asgi_application  # type: ignore[import-untyped]
+        return cast(ASGIApp, get_asgi_application())
     except ImportError as e:
         logger.error(f"Failed to load Django application: {e}")
         return None