Add IconCaptcha (#3431)

Add IconCaptcha.

README.md

@@ -1292,6 +1292,7 @@ Software that does not fit in another section.
 - [Flox](https://github.com/devfake/flox) `⚠` - Self hosted movie, TV series and anime watch list with a 3-point rating system. Uses The Movie Database backend for information. ([Demo](https://flox-demo.pyxl.dev/)) `MIT` `PHP`
 - [google-webfonts-helper](https://github.com/majodev/google-webfonts-helper) `⚠` - Hassle-Free Way to Self-Host Google Fonts. Get eot, ttf, svg, woff and woff2 files + CSS snippets. ([Demo](https://google-webfonts-helper.herokuapp.com/)) `MIT` `Nodejs`
 - [graph-vl](https://github.com/verifid/graph-vl) - Identity document verification using Machine Learning and GraphQL. `MIT` `Python`
+- [IconCaptcha](https://www.fabianwennink.nl/projects/IconCaptcha/) - IconCaptcha is a self-hosted, fast, simple and user-friendly captcha for PHP. ([Source Code](https://github.com/fabianwennink/IconCaptcha-Plugin-jQuery-PHP)) `MIT` `PHP`
 - [Journal](https://github.com/inoda/journal) - Simple journaling with encrypted entries and sharing capabilities. `MIT` `Ruby`
 - [King Phisher](https://github.com/rsmusllp/king-phisher) - King Phisher is a tool for testing and promoting user awareness by simulating real world phishing attacks. `BSD-3-Clause` `Python`
 - [Koillection](https://koillection.github.io/) - Koillection is a service allowing users to manage any kind of collections. ([Source Code](https://github.com/koillection/koillection)) `MIT` `PHP`