Fix Mixx URL (rms-open-letter#2554)

Author: tieguy

statements.md

@@ -7,7 +7,7 @@ title: Statements by other organizations on the reappointment of RMS to the FSF
 - [EFF](https://www.eff.org/deeplinks/2021/03/statement-re-election-richard-stallman-fsf-board)
 - [FSFE](https://fsfe.org/news/2021/news-20210324-01.en.html)
 - [KDE](https://ev.kde.org//2021/03/24/on-the-reappointment-of-rms-fsf/)
-- [Mixxx](https://mixxx.org/news/2021-03-26-a-statement-on-richard-stallman-and-the-free-software-foundation/)
+- [Mixxx](https://mixxx.org/news/2021-03-26-fsf-statement/)
 - [OSI](https://opensource.org/OSI_Response)
 - [Organization for Ethical Source](https://ethicalsource.dev/blog/statement-on-richard-stallman/)
 - [Outreachy](https://www.outreachy.org/blog/2021-03-23/fsf-participation-barred/)