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

[Yosef Or Boczko <yoseforb src gnome org>]

commit 1ad9439585071ca39df4682b70d0c5a7e49cf47c
Author: Yosef Or Boczko <yoseforb src gnome org>
Date:   Fri May 23 00:09:43 2014 +0300

    build: Bump required GTK+ version
    
    https://bugzilla.gnome.org/show_bug.cgi?id=730597

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index e159932..0827d46 100644
--- a/configure.ac
+++ b/configure.ac
@@ -86,7 +86,7 @@ dnl Check that we meet the  dependencies
 dnl ==============================================
 
 GLIB_REQUIRED_VERSION=2.39.91
-GTK_REQUIRED_VERSION=3.11.1
+GTK_REQUIRED_VERSION=3.13.0
 PA_REQUIRED_VERSION=2.0
 CANBERRA_REQUIRED_VERSION=0.13
 GDKPIXBUF_REQUIRED_VERSION=2.23.0