new icon: racket (original, plain, line)

[weh]

Double check these details before you open a PR

• [x] PR does not match another non-stale PR currently opened
• [x] PR name matches the format new icon: Icon name (versions separated by comma). More details here
• [x] PR's base is the develop branch.
• [x] Your icons are inside a folder as seen here
• [x] SVG matches the standards laid out here
• [x] A new object is added in the devicon.json file at the correct alphabetic position as seen here

This PR closes NONE

closes #894

Link to prove your SVG is correct and up-to-date.

https://racket-lang.org/

[github-actions[bot]]

Hi!

I'm the check-bot and we have some issues with your PR:

devicon.json is not sorted correctly.
Please make sure that your icon is added in the `devicon.json` file at the correct alphabetic position
as seen here: https://github.com/devicons/devicon/wiki/Updating-%60devicon.json%60

Check our CONTRIBUTING guide for more details regarding these errors.

Please address these issues. When you update this PR, I will check your SVGs again.

Thanks for your help, SVG-Checker Bot :smile: