docs: remove Literal as it is not being used (#2149)

This PR removes the use of `from typing import Literal` since it is not
being used in the code implementation

docs/docs/tutorials/introduction.ipynb

@@ -553,9 +553,6 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "from typing import Literal\n",
-    "\n",
-    "\n",
     "def route_tools(\n",
     "    state: State,\n",
     "):\n",
@@ -2653,7 +2650,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "from typing import Annotated, Literal\n",
+    "from typing import Annotated\n",
     "\n",
     "from langchain_anthropic import ChatAnthropic\n",
     "from langchain_community.tools.tavily_search import TavilySearchResults\n",