Update changelog for 2.0.4-1 release

debian/changelog

+php-composer-xdebug-handler (2.0.4-1) unstable; urgency=medium
+
+  [ John Stevenson ]
+  * Fix isXdebugActive if used before instantiation
+  * Prepare 2.0.4
+
+  [ David Prévot ]
+  * Track version 2 for now (bookworm?)
+
+ -- David Prévot <taffit@debian.org>  Wed, 05 Jan 2022 09:43:40 -0400
+
 php-composer-xdebug-handler (2.0.3-1) unstable; urgency=medium
 
   [ John Stevenson ]