Replace x11/zenity with version 3.x (was Re: wip/zenity: Request for review)

[Dan Cîrnaț <dan%alt.md@localhost>]

The version in wip/zenity is 3.32.0, while x11/zenity is at 2.32.1
Only wm/marco and x11/gdm(is anyone using gdm-2.x?) have
x11/zenity as dependency.
OpenBSD, Gentoo, Debian, Arch only have zenity-3.x in their repos.

I propose to drop zenity-2.x from pkgsrc. It's an old version that
depends on GTK2. Posting here since as there's been concerns
about the change in another discussion.

Are there any objections? The alternative would be to import
wip/zenity as x11/zenity3 and have a `zenity3` binary name.

Best,
Dan