gnome-themes-extra: update to version 3.28

Use gnome stable livecheck.

gnome/gnome-themes-extra/Portfile

@@ -3,7 +3,7 @@
 PortSystem          1.0
 
 name                gnome-themes-extra
-version             3.27.92
+version             3.28
 set branch          [join [lrange [split ${version} .] 0 1] .]
 categories          gnome
 maintainers         {devans @dbevans} openmaintainer
@@ -20,9 +20,9 @@ master_sites        gnome:sources/$name/$branch/
 
 use_xz              yes
 
-checksums           rmd160  aa89e277aee62007090205839288946db99282f4 \
-                    sha256  95711f95da892a0d5531a4a233546e14b123721ecd90e02a837f27e1d2d35c12 \
-                    size    2957404
+checksums           rmd160  0f083d9970389a2eb1fc08da54c4759414d2b162 \
+                    sha256  7c4ba0bff001f06d8983cfc105adaac42df1d1267a2591798a780bac557a5819 \
+                    size    2953272
 
 depends_build       port:intltool \
                     port:pkgconfig \
@@ -60,4 +60,4 @@ if {![variant_isset quartz]} {
     default_variants +x11
 }
 
-livecheck.type      gnome-with-unstable
+livecheck.type      gnome