gtksourceview-3.0: remove from GIR_BINDINGS
gtksourceview-3.0: remove from GIR_BINDINGS

gtksourceview distributes bindings upstream these days, no need to
keep the deprecated copy in the Vala repository updated.

spidermonkdust/vala,rvu95/vala,frida/vala,GNOME/vala,GNOME/vala,rvu95/vala,frida/vala,frida/vala,GNOME/vala,frida/vala,spidermonkdust/vala,spidermonkdust/vala,GNOME/vala,frida/vala,rvu95/vala