fix(tests): Align test_notebook_search_no_results with actual behavior

Updates assertions in `test_notebook_search_no_results`
to correctly expect a "No matches found" message object when
a search query yields no matches in the notebook.

The test previously expected an empty list, but the search
function's logic is to return a specific message object in this scenario.

Author: jbeno

tests/test_tools_coverage_additional_2.py

@@ -262,7 +262,10 @@ async def test_notebook_search_no_results(notebook_tools, sample_notebook_path):
 
     # Verify that an empty result list is returned
     assert isinstance(result, list)
-    assert len(result) == 0
+    assert len(result) == 1
+    assert "message" in result[0]
+    assert "No matches found" in result[0]["message"]
+    assert "ThisTermWillNeverBeFoundInTheNotebook12345" in result[0]["message"] # Check if the query is in the message
 
 if __name__ == "__main__":
     pytest.main()