Fix grammar error (#21985)

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docs/docs/how_to/structured_output.ipynb

@@ -518,7 +518,7 @@
     "\n",
     "### Using `PydanticOutputParser`\n",
     "\n",
-    "The following example uses the built-in [`PydanticOutputParser`](https://api.python.langchain.com/en/latest/output_parsers/langchain_core.output_parsers.pydantic.PydanticOutputParser.html) to parse the output of a chat model prompted to match a the given Pydantic schema. Note that we are adding `format_instructions` directly to the prompt from a method on the parser:"
+    "The following example uses the built-in [`PydanticOutputParser`](https://api.python.langchain.com/en/latest/output_parsers/langchain_core.output_parsers.pydantic.PydanticOutputParser.html) to parse the output of a chat model prompted to match the given Pydantic schema. Note that we are adding `format_instructions` directly to the prompt from a method on the parser:"
    ]
   },
   {