move generated stubs to separate directory, too messty

django-stubs-generated/db/backends/postgresql/client.pyi

@@ -0,0 +1,10 @@
+from typing import Any, Dict, Optional
+
+from django.db.backends.base.client import BaseDatabaseClient
+
+
+class DatabaseClient(BaseDatabaseClient):
+    executable_name: str = ...
+    @classmethod
+    def runshell_db(cls, conn_params: Dict[str, str]) -> None: ...
+    def runshell(self) -> None: ...