[Test] change k settings for test_topk_insert

several channels getting out the same value, causing different
topk outputs from npy and finn

tests/transformation/test_topk_insert.py

@@ -21,7 +21,7 @@ import pytest
 export_onnx_path = "test_topk_insert.onnx"
 
 
-@pytest.mark.parametrize("k", [1, 5, 10])
+@pytest.mark.parametrize("k", [1, 2])
 def test_topk_insert(k):
     tfc = get_test_model_trained("TFC", 1, 1)
     bo.export_finn_onnx(tfc, (1, 1, 28, 28), export_onnx_path)