[gnome-usage] build: Require Gtk+ >= 3.20.10

[Gitlab System User <gitlab src gnome org>]

commit e656a5b6a67d35526a8140592ca0c9bfaeb6a423
Author: Felipe Borges <felipeborges gnome org>
Date:   Mon Oct 2 17:04:39 2017 +0200

    build: Require Gtk+ >= 3.20.10
    
    gtk_widget_class_set_css_name requires gtk+ >= 3.20

 meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index f3ec09d..33cc824 100644
--- a/meson.build
+++ b/meson.build
@@ -5,7 +5,7 @@ cc = meson.get_compiler('c')
 glib = dependency('glib-2.0', version : '>=2.38')
 gobject = dependency('gobject-2.0')
 gio = dependency('gio-2.0')
-gtk = dependency('gtk+-3.0')
+gtk = dependency('gtk+-3.0', version : '>=3.20.10')
 gtop = dependency('libgtop-2.0', version : '>=2.34.2')
 math = cc.find_library('m')