eclass/gnome.org: upgrade for EAPI 7 support

versionator is deprecated in EAPI 7.

BUG=chromium:1099508
TEST=build

Change-Id: I3ea4c980179b6cfbb1fdc94d9977a734961dcb3e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/2268631
Tested-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Allen Webb <allenwebb@google.com>
Commit-Queue: Brian Norris <briannorris@chromium.org>
1 file changed