Upgrade to ruby 3.0

[zendesk-mattlefevre]

Description

The time has come: We're working on bumping Samson to Ruby 3.0

Risks

• High - 2.7 to 3.0 is a big jump with some breaking changes.

[grosser]

best do the gem upgrades in 1-off PRs to lower the risk / complexity🤞

[grosser]

unable to reproduce the cleanliness error (was unable to get 3.0 installed so I used 3.1, so maybe if that works bump to that ...)

[grosser]

oh ... it's a random error, ran it a few times and it fails :D

[grosser]

use this in test/integration/cleanliness_test.rb:8

- def all_models
+ let_all(:all_models) do