gpredict: add missing dependency librsvg

Fixes non-fatal runtime error.

(gpredict:68381): Gtk-WARNING **: 17:19:54.971: Error loading icon from file '/opt/local/share/pixmaps/gpredict/logos/gpredict_icon_color.svg':
	Couldn’t recognize the image file format for file “/opt/local/share/pixmaps/gpredict/logos/gpredict_icon_color.svg”

science/gpredict/Portfile

@@ -5,7 +5,7 @@ PortGroup           perl5 1.0
 
 name                gpredict
 version             2.2.1
-revision            2
+revision            3
 categories          science
 license             GPL-2+
 platforms           darwin
@@ -35,6 +35,7 @@ perl5.branches      5.28
 depends_build       port:intltool \
                     port:pkgconfig
 depends_lib         port:goocanvas2 \
+                    port:librsvg \
                     port:curl
 
 configure.env-append \