Update project URL

The upstream project has recently moved through the following series of URLs:

Project URL	Related commit
https://github.com/ioquatix/sus/	-
https://github.com/sus-rb/sus	3d25780 Update links.
https://github.com/suspecting/sus	fa216fe Update organisation name.
https://github.com/socketry/sus/	1ae7b94 Move gem to socketry organization.