Adyen::Client#service_base_url logic is incorrect making the DisputesAPI unusable

[timnovinger]

Describe the bug
When the DisputesAPI portion of the client gem was updated (it appears around version 8) to use disputes instead of dispute it broke the logic in the service_url_base method due to the Adyen::Service::Disputes class using "Disputes" as the service variable instead of "DisputeService".

https://github.com/Adyen/adyen-ruby-api-library/blob/v10.1.0/lib/adyen/client.rb#L72
https://github.com/Adyen/adyen-ruby-api-library/blob/v10.1.0/lib/adyen/services/disputes.rb#L13

How to reproduce
Attempt to use any of methods within the Adyen::Service::Disputes class and you will met with an Invalid service specified error.

Expected behavior
A successful request.

Screenshots
N/A

Desktop (please complete the following information):

• ruby Version: ruby 3.0.1p64 (2021-04-05 revision 0fb782ee38) [x86_64-linux]
• Library Version: 10.1.0

Additional context
Add any other context about the problem here.