docs: imported List is not used (#20720)

# Description

Minor sample code fix

# Issue

Imported `List` is not used.

# Dependencies

N/A

# Twitter handle

N/A

docs/docs/modules/model_io/output_parsers/types/json.ipynb

@@ -20,8 +20,6 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "from typing import List\n",
-    "\n",
     "from langchain_core.output_parsers import JsonOutputParser\n",
     "from langchain_core.prompts import PromptTemplate\n",
     "from langchain_core.pydantic_v1 import BaseModel, Field\n",