Update readme.txt

Co-authored-by: Dovid Levine <david@axepress.dev>

Author: colinmurphy

readme.txt

@@ -2,7 +2,7 @@
 Contributors: blakewpe, chriswiegman, joefusco, matthewguywright, TeresaGobble, thdespou, wpengine
 Tags: faustjs, faust, headless, decoupled, gutenberg
 Requires at least: 5.7
-Tested up to: 6.8.0
+Tested up to: 6.8
 Stable tag: 4.8.2
 Requires PHP: 7.4
 License: GPLv2 or later