PosMobile service does not have a configured service_url_base

[davidjrice]

Describe the bug
Cannot use the provided PosMobile service as it does not have a configured service_url_base

How to reproduce

client = Adyen::Client.new()
pos = Adyen::PosMobile.new()
pos.create_communication_session(request)
=> /usr/local/bundle/gems/adyen-ruby-api-library-9.4.0/lib/adyen/client.rb:90:in `service_url_base': Invalid service specified (ArgumentError)

Expected behavior
An Adyen::AdyenResult should be returned

Desktop (please complete the following information):

• ruby Version: 3.2.2
• Library Version: 9.4.0