Ruby 3.3

[Earlopain]

Test against Ruby 3.3 and supress new warnings.

Ruby 3.3 will warn if base64 or bigdecimal is required without requiring it in the gemspec. The base64 gem is trivial to replace, but bigdecimal I added to the gemspec.

base64:

• Remove base64 dependency rack/rack#2110
• [Fix #12310] Drop base64 gem from runtime dependency rubocop/rubocop#12313
• Remove runtime dependency on base64 newrelic/newrelic-ruby-agent#2378
• Remove runtime dependency on base64 lostisland/faraday#1541

bigdecimal:

• Add bigdecimal to runtime dependency rails/rails#49039

[Earlopain]

@sferik could you check this out if you got some time?

[Earlopain]

Thank you!