fix: update types for insert (#187)

Co-authored-by: [email protected] <[email protected]>

Author: J0

postgrest/_async/request_builder.py

@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from typing import Optional
+from typing import Optional, Union
 
 from httpx import Headers, QueryParams
 from pydantic import ValidationError
@@ -229,7 +229,7 @@ def select(
 
     def insert(
         self,
-        json: dict,
+        json: Union[dict, list],
         *,
         count: Optional[CountMethod] = None,
         returning: ReturnMethod = ReturnMethod.representation,