Update ruby version for rvm install in /doc/PREQUISITES.md

[kofosu2289]

Fixes #8497 (<=== Add issue number here)

Make sure these boxes are checked before your pull request (PR) is ready to be reviewed and merged. Thanks!

• PR is descriptively titled 📑 and links the original issue above 🔗
• tests pass -- look for a green checkbox ✔️ a few minutes after opening your PR -- or run tests locally with rake test
• code is in uniquely-named feature branch and has no merge conflicts 📁
• screenshots/GIFs are attached 📎 in case of UI updation
• ask @publiclab/reviewers for help, in a comment below

We're happy to help you get this ready -- don't be afraid to ask for help, and don't be discouraged if your tests fail at first!

If tests do fail, click on the red X to learn why by reading the logs.

Please be sure you've reviewed our contribution guidelines at https://publiclab.org/contributing-to-public-lab-software

Thanks!

[welcome]

Thanks for opening this pull request! This space is protected by our Code of Conduct - and we're here to help.
Dangerbot will test out your code and reply in a bit with some pointers and requests.
Also please refer here for installation help 💿
There may be some errors, but don't worry! We'll work through them with you! 👍🎉😄
It would be great if you can tell us your Twitter handle so we can thank you properly?

[gitpod-io]

[codeclimate]

Code Climate has analyzed commit 8d615a9 and detected 0 issues on this pull request.

View more on Code Climate.

[codecov]

Codecov Report

Merging #8502 into main will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #8502   +/-   ##
=======================================
  Coverage   82.01%   82.01%           
=======================================
  Files         101      101           
  Lines        5894     5894           
=======================================
  Hits         4834     4834           
  Misses       1060     1060           

[RuthNjeri]

It looks good to me @kofosu2289 👍🏾

[jywarren]

This looks perfect, thanks so much - to both @kofosu2289 and to @RuthNjeri for creating and supporting this! Great job both of you -- merging this now, and congrats!!!

[welcome]

Congrats on merging your first pull request! 🙌🎉⚡️
Your code will likely be published to PublicLab.org in the next few days, but first it will be published to https://stable.publiclab.org/ (it will take some minutes for this to load, and until then you may see logs from the build process). Please test out your work on this testing server and report back with a comment that all has gone well!
Do join our weekly check-in to share your this week goal and the awesome work you did 😃. Please find the link pinned in the issue section 📝
Now that you've completed this, you can help someone else take their first step!
Reach out to someone else working on theirs on Public Lab's code welcome page (where you'll now be featured as a recent contributor!). Thanks!

Help others take their first step

Now that you've merged your first pull request, you're the perfect person to help someone else out with this challenging first step. 🙌

https://code.publiclab.org

Try looking at this list of `first-timers-only` issues, and see if someone else is waiting for feedback, or even stuck! 😕

People often get stuck at the same steps, so you might be able to help someone get unstuck, or help lead them to some documentation that'd help. Reach out and be encouraging and friendly! 😄 🎉

Read about how to help support another newcomer here, or find other ways to offer mutual support here.