[ICON REQUEST]: Mastodon

### I have searched through the issues and didn't find my problem.

- [X] Confirm

### About the icon

Mastodon is an important social media site used by developers, techies, & nerds. If Twitter & Facebook are in this project, Mastodon should be as well.

### Links and sources

Official branding page: https://joinmastodon.org/branding

Font Awesome: https://fontawesome.com/search?q=mastodon&o=r

### Icon links and previews

#### Mastodon purple

https://joinmastodon.org/logos/logo-purple.svg

#### Mastodon black

https://joinmastodon.org/logos/logo-black.svg

#### Mastodon white

https://joinmastodon.org/logos/logo-white.svg

### Additional information

_No response_