add more tests with negative slices

tests/kernelcreation/test_iteration_slices.py

@@ -62,6 +62,8 @@ def test_sliced_iteration():
         make_slice[3, 2:-2],
         make_slice[2:-2:2, ::3],
         make_slice[10:, :-5:2],
+        make_slice[-5:-1, -1],
+        make_slice[-3, -1]
     ],
 )
 def test_numerical_slices(gen_config: CreateKernelConfig, xp, islice):