remove potential json key conflict in passing arguments

Author: Tom1204

python_graphql_client/graphql_client.py

@@ -71,8 +71,12 @@ async def execute_async(
         async with aiohttp.ClientSession() as session:
             async with session.post(
                 self.endpoint,
-                json=request_body,
-                **{**self.options, **kwargs, "headers": {**self.headers, **headers}},
+                **{
+                    **self.options,
+                    **kwargs,
+                    "headers": {**self.headers, **headers},
+                    "json": request_body,
+                },
             ) as response:
                 return await response.json()