Made a grammatical correction in streaming.ipynb (#21707)

The only change is replacing the word "operators" with "operates," to
make the sentence grammatically correct.

Thank you for contributing to LangChain!

- [x] **PR title**: "docs: Made a grammatical correction in
streaming.ipynb to use the word "operates" instead of the word
"operators""


- [x] **PR message**: 
- **Description:** The use of the word "operators" was incorrect, given
the context and grammar of the sentence. This PR updates the
documentation to use the word "operates" instead of the word
"operators".
    - **Issue:** Makes the documentation more easily understandable.
    - **Dependencies:** -no dependencies-
    - **Twitter handle:** --


- [x] **Add tests and docs**: Since no new integration is being made, no
new tests/example notebooks are required.


- [x] **Lint and test**: Run `make format`, `make lint` and `make test`
from the root of the package(s) you've modified. See contribution
guidelines for more: https://python.langchain.com/docs/contributing/
    - **No formatting changes made to the documentation**

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- Make sure optional dependencies are imported within a function.
- Please do not add dependencies to pyproject.toml files (even optional
ones) unless they are required for unit tests.
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If no one reviews your PR within a few days, please @-mention one of
baskaryan, efriis, eyurtsev, hwchase17.

docs/docs/how_to/streaming.ipynb

@@ -447,7 +447,7 @@
     "Le'ts fix the streaming using a generator function that can operate on the **input stream**.\n",
     "\n",
     ":::{.callout-tip}\n",
-    "A generator function (a function that uses `yield`) allows writing code that operators on **input streams**\n",
+    "A generator function (a function that uses `yield`) allows writing code that operates on **input streams**\n",
     ":::"
    ]
   },