remove Snibox (unmaintained since 2019) (#3707)

- ref. #3558

README.md

@@ -1522,7 +1522,6 @@ A [pastebin](https://en.wikipedia.org/wiki/Pastebin) is a type of online content
 - [prologic pastebin](https://git.mills.io/prologic/pastebin) - Simple pastebin service with convenient api and CLI. ([Demo](https://paste.mills.io)) `MIT` `Go`
 - [PurritoBin](https://github.com/PurritoBin/PurritoBin) - Ultra fast, minimalistic, encrypted command line paste-bin, where the server has no knowledge of the paste data. `ISC` `C++`
 - [rustypaste](https://github.com/orhun/rustypaste) - A minimal file upload/pastebin service. `MIT` `Rust`
-- [Snibox](https://snibox.github.io/) - Code snippets manager with attractive tag-oriented interface. ([Source Code](https://github.com/snibox/snibox)) `MIT` `Ruby`
 - [snipt](https://github.com/nicksergeant/snipt) - Long-term memory for coders. Share and store code snippets. `MIT` `Python`
 - [SnyPy](https://snypy.com) - Open source on-prem code snippet manager. ([Demo](https://app.snypy.com), [Source Code](https://github.com/snypy)) `MIT` `Docker`
 - [SocksBin](https://github.com/magnumdingusedu/socksbin) - Simple and fast terminal based pastebin, with optional code highlighting. No specific client required, all you need is netcat. `GPL-3.0` `Python`