TST: Avoid hashing np.timedelta64 without unit (#60416)

Author: mroeschke

pandas/tests/test_algos.py

@@ -1254,7 +1254,7 @@ def test_value_counts_nat(self):
         result_dt = algos.value_counts_internal(dt)
         tm.assert_series_equal(result_dt, exp_dt)
 
-        exp_td = Series({np.timedelta64(10000): 1}, name="count")
+        exp_td = Series([1], index=[np.timedelta64(10000)], name="count")
         result_td = algos.value_counts_internal(td)
         tm.assert_series_equal(result_td, exp_td)