Allow use of `public_suffix` 5
Allow use of `public_suffix` 5

Changes in public_suffix looks fine to me, no breaking API changes what I can see:

* https://github.com/weppos/publicsuffix-ruby/blob/v5.0.0/CHANGELOG.md#500
* https://github.com/weppos/publicsuffix-ruby/compare/v4.0.7...v5.0.0

Addressable 2.8.1 was just released to allow use of public_suffix 5.x:
https://github.com/sporkmonger/addressable/blob/addressable-2.8.1/CHANGELOG.md#addressable-281

twingly/twingly-url