x11-toolkits/gtk40: enable GSTREAMER by default

Required for Gtk.MediaFile by video-trimmer and fractal >= 5 e.g.,

  $ video-trimmer foo.mp4
  (video-trimmer:12345): VideoTrimmer-WARNING **: src/video_preview.rs:142: Error in MediaFile: GTK could not find a media module. Check your installation.

x11-toolkits/gtk40/Makefile

@@ -1,5 +1,6 @@
 PORTNAME=	gtk
 PORTVERSION=	4.8.2
+PORTREVISION=	1
 CATEGORIES=	x11-toolkits
 MASTER_SITES=	GNOME
 PKGNAMESUFFIX=	4
@@ -47,7 +48,7 @@ GLIB_SCHEMAS=	org.gtk.Demo4.gschema.xml \
 
 OPTIONS_DEFINE=	CUPS COLORD DEBUG BROADWAY FFMPEG \
 		GSTREAMER VULKAN WAYLAND X11
-OPTIONS_DEFAULT=CUPS COLORD BROADWAY VULKAN WAYLAND X11
+OPTIONS_DEFAULT=CUPS COLORD BROADWAY GSTREAMER VULKAN WAYLAND X11
 OPTIONS_SUB=	yes
 
 BROADWAY_DESC=	Enable GDK Broadway backend for showing GTK+ in the webbrowser using HTML5 and web sockets.