[aisleriot] build: Require GTK 3.18

[Jeremy Bicha <jbicha src gnome org>]

commit dec58f4a4b3b326bb04b6338c4fb568c928ef59e
Author: Jeremy Bicha <jbicha ubuntu com>
Date:   Sun Jan 6 21:31:29 2019 -0500

    build: Require GTK 3.18
    
    for Keyboard Shortcuts feature

 configure.ac | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/configure.ac b/configure.ac
index 635d420f..b467ec5e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -267,7 +267,7 @@ AM_CONDITIONAL([ENABLE_DEBUG_UI],[test "$enable_debug_ui" = "yes"])
 # ********************
 
 case "$with_gtk" in
-  3.0) GTK_REQUIRED=3.4.0
+  3.0) GTK_REQUIRED=3.18.0
        RSVG_REQUIRED=2.32.0
        LIBCANBERRA_GTK_REQUIRED=0.26
        LIBCANBERRA_GTK_PKGS="libcanberra-gtk3 >= $LIBCANBERRA_GTK_REQUIRED"