graphics/rubygem-mini_magick: Update to 4.12.0

Changes:	https://github.com/minimagick/minimagick/releases

graphics/rubygem-mini_magick/Makefile

 PORTNAME=	mini_magick
-PORTVERSION=	4.11.0
+PORTVERSION=	4.12.0
 CATEGORIES=	graphics rubygems
 MASTER_SITES=	RG
 

graphics/rubygem-mini_magick/distinfo

-TIMESTAMP = 1642102659
-SHA256 (rubygem/mini_magick-4.11.0.gem) = 1a8abef753110e7362d221cad76046a52c701c1a144049979e37b5103a0146aa
-SIZE (rubygem/mini_magick-4.11.0.gem) = 18944
+TIMESTAMP = 1674590522
+SHA256 (rubygem/mini_magick-4.12.0.gem) = 67302fa84e63f1002b71416a8466968ed0f33d22f5d42962a0c09a9f1c3a906a
+SIZE (rubygem/mini_magick-4.12.0.gem) = 18944