Bump dependencies for Rails 7.1

[justisb]

Bumps activemodel and activesupport dependency ranges to allow Rails 7.1, which was released two weeks ago.

[justisb]

Looks like currently the RSpec suite is broken because Rails introduced their own Object#with monkey patch that interferes with the RSpec expect(x).to receive(:foo).with('bar') tests.

Waiting to see if there ends up being a resolution here: rspec/rspec-rails#2699

[justisb]

Actually just upgrading RSpec (or specifically the rspec-mocks child dependency) appears to have solved it.

[thhermansen]

Thank you :)