test_numbertheory: 0 for inverse_mod

ensure that the inverse_mod with 0 works correctly

Author: tomato42

src/ecdsa/test_numbertheory.py

@@ -259,3 +259,6 @@ def test_inverse_mod(self, nums):
 
         assert 0 < inv < mod
         assert num * inv % mod == 1
+
+    def test_inverse_mod_with_zero(self):
+        assert 0 == inverse_mod(0, 11)