Update ISC LICENSE

This license had an unfortunate wording choice: it provided recipients with “Permission to use, copy, modify, and distribute this software…” This was the same language from the license of Pine that the University of Washington later claimed prohibited people from distributing modified versions of the software.

ISC has told us they do not share the University of Washington's interpretation, and we have every reason to believe them. ISC also updated the license to read “Permission to use, copy, modify, and/or distribute this software…” While the inclusion of “and/or” doesn't completely solve the issue, there's no reason to avoid software released under this license.

So there's that, so I updated ISC License and now it is up-to-date :P.

Oh and also I updated year from 2018 to 2018-2019, not really important, but nuh 🤷.