[gnome-control-center] keyboard: Bump required GTK+ version

[Bastien Nocera <hadess src gnome org>]

commit 13b745aa3df77c347a98ae8b2ef137ed8bc20483
Author: Bastien Nocera <hadess hadess net>
Date:   Fri Jul 29 19:01:32 2016 +0200

    keyboard: Bump required GTK+ version
    
    As the newly public GtkShortcutLabel is needed for that panel.

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 4abb5de..3f4e113 100644
--- a/configure.ac
+++ b/configure.ac
@@ -86,7 +86,7 @@ dnl Check that we meet the  dependencies
 dnl ==============================================
 
 GLIB_REQUIRED_VERSION=2.44.0
-GTK_REQUIRED_VERSION=3.20.3
+GTK_REQUIRED_VERSION=3.21.4
 PA_REQUIRED_VERSION=2.0
 CANBERRA_REQUIRED_VERSION=0.13
 GDKPIXBUF_REQUIRED_VERSION=2.23.0