Update canonical-data.json in ISBN Verifier

Added a check where position of X is not at last position
def test_all_xs(self):
self.assertIs(is_valid(“XXXXXXXXXX”), False)

See existing test 28025280-2c39-4092-9719-f3234b89c627.

Would be great to see an incorrect solution that passes the current test suite so we can figure out together how best to extend it.