Create a gem named archiver which will add archive, restore and archived? methods to an ActiveRecord model.

1. Create a gem named archiver.
2. Ensure it has a valid gemspec file.
3. Add activerecord as a runtime dependency.

The archive, restore, and archived? methods should work based on the archived_at field on the active record model. The gem's assumption is that it will be used on models that already have the archived_at field.

1. Add archive method to set archived_at to the current time.
2. Add restore method to set archived_at to nil.
3. Add archived? method to check if archived_at is set.

We will use this repo to test functionality:

Starter Repo

Note: cd into the repo after cloning and run rm -rf .git to avoid git submodule usage

1. Clone the repo and get it running.
2. Add the factory_bot gem to the development and test group.
3. Ensure the factory_bot gem is greater than or equal to 5.0.0 but less than 6.0.0.
4. Add the archiver gem as a local gem and include the Archiver functionality into the Article model.
5. Make sure that the added Archiver functionality works in the blog by testing it on articles.