docs: update test line references in MessagePack section

[WolfMTK]

Description

Fixed a typo has been corrected in the strings pertaining to request testing with MessagePack.

Closes

[sobolevn]

For future PRs: please attach links to changed file numbers / screenshots of the changed docs.

Thank you!

The change seems correct:

litestar/tests/examples/test_request_data.py

Lines 140 to 145 in 9df67e2

	def test_msgpack_app() -> None:
	test_data = {"name": "Moishe Zuchmir", "age": 30, "programmer": True}
	with TestClient(app=msgpack_app) as client:
	response = client.post("/", content=encode_msgpack(test_data))
	assert response.json() == test_data