x11-toolkits/rubygem-gtksourceview3: Update to 4.2.6

Changes:	https://github.com/ruby-gnome/ruby-gnome/releases
		https://github.com/ruby-gnome/ruby-gnome/blob/main/NEWS.md

x11-toolkits/rubygem-gtksourceview3/Makefile

 PORTNAME=	gtksourceview3
-PORTVERSION=	4.2.5
+PORTVERSION=	4.2.6
 CATEGORIES=	x11-toolkits rubygems
 MASTER_SITES=	RG
 

x11-toolkits/rubygem-gtksourceview3/distinfo

-TIMESTAMP = 1735228224
-SHA256 (rubygem/gtksourceview3-4.2.5.gem) = ab82d5d0c302ff79970d7a93ec36c19403ded78a6c316397a0eeabec1ce5054f
-SIZE (rubygem/gtksourceview3-4.2.5.gem) = 16896
+TIMESTAMP = 1738090210
+SHA256 (rubygem/gtksourceview3-4.2.6.gem) = c074d4f9cda7197781cf9d805a6df24a0b741a3da142ff9e9f9d084f8e33f6de
+SIZE (rubygem/gtksourceview3-4.2.6.gem) = 16896