Release to experimental.

debian/changelog

@@ -1,4 +1,4 @@
-qt6-base (6.4.0+dfsg-1) UNRELEASED; urgency=medium
+qt6-base (6.4.0+dfsg-1) experimental; urgency=medium
 
   [ Patrick Franz ]
   * New upstream release (6.4.0).
@@ -8,7 +8,7 @@ qt6-base (6.4.0+dfsg-1) UNRELEASED; urgency=medium
   * Update symbols from buildlogs.
   * Update lintian-overrides.
 
- -- Debian Qt/KDE Maintainers <debian-qt-kde@lists.debian.org>  Sat, 01 Oct 2022 19:38:04 +0200
+ -- Patrick Franz <deltaone@debian.org>  Sat, 01 Oct 2022 20:35:52 +0200
 
 qt6-base (6.3.1+dfsg-10) unstable; urgency=medium