Update Ruby on Rails dependency to >= 7.1 (7.0 EOL on 2025/4/5);

[strouptl]

Update required Ruby on Rails version to >= 7.1, since 7.0 reaches EOL on 2025/4/5.

Resolves issue with failing CI tests on master branch due to a compatibility issue between Rails 7.0, and the latest version of concurrent-ruby (1.3.5), which was released on February 5th.

References:

• Rails 7.0 EOL notice: https://rubyonrails.org/2024/10/15/new-maintenance-policy-and-eol-annouments
• Ruby on Rails issue: Rails 7.0.8 fails to create an app with most recent concurrent-ruby version rails/rails#54260