Compatibility with rails 8.0

[dlupu]

Hello Scalingo Team,

Any chance you could bump up the gemspec to make the gem compatible with Ruby on Rails 8.0?

Currently getting this error message:

Could not find compatible versions05:27
Because scalingo >= 3.1.0 depends on activesupport >= 5, < 8
  and scalingo < 3.1.0 depends on activesupport >= 5, < 7,
  activesupport >= 5, < 8 is required.
So, because rails >= 8.0.1 depends on activesupport = 8.0.1
  and Gemfile depends on rails ~> 8.0.1,
  version solving has failed.

[aurelien-reeves-scalingo]

Thanks for your report

We'll have a look as soon as possible

That being said, we are a bit swamped at the moment, but if you'd like to put up a PR we can merge