Remove outdated comparison

Author: rgrove

COMPARISON.md

@@ -31,7 +31,6 @@ Links
 * [Issues](https://github.com/rgrove/sanitize/issues)
 * [Release History](https://github.com/rgrove/sanitize/blob/master/HISTORY.md#sanitize-history)
 * [Online Demo](https://sanitize-web.fly.dev/)
-* [Biased comparison of Ruby HTML sanitization libraries](https://github.com/rgrove/sanitize/blob/master/COMPARISON.md)
 
 Installation
 -------------