prevent uri extraction loop to max of 100

URI extraction with use_hacks=True

A link with a trailing "." was creating a "infinite" loop which was only broken due to a counterlimit of 100.

        txt = "http://www.domain-invalid.com/bla."
        uris = self.candidate.extracturis(txt, use_hacks=True)
        print(f"uris: {uris}")
        self.assertIn("http://www.domain-invalid.com/bla", uris)