Ruby 3.1 fails unit tests

[osowskit]

Issue Type: Bug

Description:

GitHub was using Ruby 3.1 for this action which resulted in a failure. We will need to resolve this when adding support for Ruby 3.1

Expected Result:

all tests pass

Actual Result:

https://github.com/twitterdev/twitter-ruby-ads-sdk/actions/runs/1665253545

Steps to Reproduce:

With Ruby 3.1.0, bundle exec rake

Relates To: #123