Update fairblue changelog

fairblue-changelog.md

 # Changelog of Fairblue development
 ## Next
+* Fix bug, where translator is muted if they change translation language
 ## 21022021
 * we disabled some audio preprocessing of the browser, it seems some of this is going nuts when there are multiple streams
 * the input device used in the echo test is now made sure to be used as the translator microphone