Do not restrain rails version + prepare for 7.2.0 release

[chaadow]

This will allow applications running on rails main/master branch to easily use the gem

• Prepare for Rails 7.2.0 release that is about to be released

Let me know if I should update Appraisals to also have a main appraisal pointing to rails main branch. Thanks

EDIT: if this is something that you may accept, please let me know, and I will further update this PR to add more checks on rails main etc..

(I don't wanna commit my time if this is gonna be discarded)