Solutions: Remove all bundler and Gemfile setup

[JoshDevHub]

Because

In #80 the instructions for this repo were changed to have users install RSpec globally. This means that the current main branch no longer has a Gemfile or anything. This is introduced an inconsistency with the solutions branch. This is especially a problem because if the user tries to checkout the solutions branch locally, the commands they used to run the tests in main will no longer function correctly.

Additionally I noticed that the README had gone very out of sync with main. I figured it'd be best to update this as well.

This PR

• Remove Gemfile, Gemfile.lock, and .ruby-version files
• Update README to match main's

Issue

Closes #XXXXX

Additional Information

Pull Request Requirements

• [x] I have thoroughly read and understand The Odin Project Contributing Guide
• [x] The title of this PR follows the location of change: brief description of change format, e.g. Data types exercise: Update spec files
• [x] The Because section summarizes the reason for this PR
• [x] The This PR section has a bullet point list describing the changes in this PR
• [ ] If this PR addresses an open issue, it is linked in the Issue section
• [ ] If this PR includes changes that needs to be updated on the solutions branch, I have created another PR (and linked it to this PR).

[JoshDevHub]

You bring up a good point @rlmoser99

I'll check with the team on moving the solutions over.

[JoshDevHub]

Closing this because the solutions branch has been merged with main per #109