docs(docs): use model_json_schema() (#32485)

While trying the line People.schema got a warning. 
```The `schema` method is deprecated; use `model_json_schema` instead```

So made the changes and now working file.

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docs/docs/how_to/structured_output.ipynb

@@ -909,7 +909,7 @@
     "        ),\n",
     "        (\"human\", \"{query}\"),\n",
     "    ]\n",
-    ").partial(schema=People.schema())\n",
+    ").partial(schema=People.model_json_schema())\n",
     "\n",
     "\n",
     "# Custom parser\n",