ada_get_domain() doesnt work if path present

[schochastics]

adaR::ada_get_domain("http://sub.google.de/test")
#> [1] NA

This is due to public_suffix() not being able to parse URLs with paths

adaR::public_suffix("http://google.de/test")
#> [1] NA
psl::public_suffix("http://google.de/test")
#> [1] "de/test"

Not sure if this should be NA instead of de. But then again, psl also fails.
For now, we fix ada_get_domain internally and reconsider public_suffix in #54