Add fork install option

[tmorrell]

:heart: Thank you for your contribution!

Description

This adds an option to install a fork in a Pipfile, with a warning that this is only recommended in limited cases. Setup mostly from @Samk13

Checklist

Ticks in all boxes and 🟢 on all GitHub actions status checks are required to merge:

• [ ] I'm aware of the code of conduct.
• [ ] I've created logical separate commits and followed the commit message format.
• [ ] I've added relevant test cases.
• [ ] I've added relevant documentation.
• [ ] I've marked translation strings.
• [ ] I've identified the copyright holder(s) and updated copyright headers for touched files (>15 lines contributions).
• [ ] I've NOT included third-party code (copy/pasted source code or new dependencies).
  • If you have added third-party code (copy/pasted or new dependencies), please reach out to an architect.

Frontend

• [ ] I've followed the CSS/JS and React guidelines.
• [ ] I've followed the web accessibility guidelines.
• [ ] I've followed the user interface guidelines.

Reminder

By using GitHub, you have already agreed to the GitHub’s Terms of Service including that:

1. You license your contribution under the same terms as the current repository’s license.
2. You agree that you have the right to license your contribution under the current repository’s license.

[tmorrell]

Thanks @fenekku, I've included all your changes.

[fenekku]

Perfect, I'll merge :+1: