[five-or-more] build: Require GTK+ >= 3.20

[Jeremy Bicha <jbicha src gnome org>]

commit 1ec40b6d5348ff5ca391d49ef412099bde5f0f93
Author: Jeremy Bicha <jbicha ubuntu com>
Date:   Tue Aug 8 11:31:21 2017 -0400

    build: Require GTK+ >= 3.20
    
    https://bugzilla.gnome.org/show_bug.cgi?id=786005

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index b6aa670..a9e24e1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -19,7 +19,7 @@ dnl Dependencies
 dnl ###########################################################################
 
 GLIB_REQUIRED=2.32
-GTK_REQUIRED=3.12.0
+GTK_REQUIRED=3.20.0
 RSVG_REQUIRED=2.32.0
 
 PKG_CHECK_MODULES(FIVE_OR_MORE, [