League/Omnipay v3

[Artistan]

https://github.com/thephpleague/omnipay-common/blob/master/UPGRADE.md

would like to have version 3 compatible

[iddqdidkfa]

Sorry. Really have not much time now. I'm not using this package in my projects at the moment, so will try to make an update after holidays . PR's are very welcome tho.