update changelog to mention --list-themes bugfix when stdout is piped

Author: keith-hall

CHANGELOG.md

@@ -3,7 +3,8 @@
 ## Features
 
 ## Bugfixes
-* Fix `BAT_THEME_DARK` and `BAT_THEME_LIGHT` being ignored, see issue #3171 and PR #3168 (@bash)
+- Fix `BAT_THEME_DARK` and `BAT_THEME_LIGHT` being ignored, see issue #3171 and PR #3168 (@bash)
+- Prevent `--list-themes` from outputting default theme info to stdout when it is piped, see #3189 (@einfachIrgendwer0815)
 
 ## Other