configure.ac: Bump version to 1.13

Signed-off-by: Jonas Ådahl <jadahl@gmail.com>
diff --git a/configure.ac b/configure.ac
index 7e16383..1cf709a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,7 +1,7 @@
 AC_PREREQ([2.64])
 
 m4_define([wayland_protocols_major_version], [1])
-m4_define([wayland_protocols_minor_version], [12])
+m4_define([wayland_protocols_minor_version], [13])
 m4_define([wayland_protocols_version],
           [wayland_protocols_major_version.wayland_protocols_minor_version])