configure.ac: Bump version to 1.4.91
diff --git a/configure.ac b/configure.ac
index 5ae843e..10e0407 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2,7 +2,7 @@
 
 m4_define([wayland_major_version], [1])
 m4_define([wayland_minor_version], [4])
-m4_define([wayland_micro_version], [0])
+m4_define([wayland_micro_version], [91])
 m4_define([wayland_version],
           [wayland_major_version.wayland_minor_version.wayland_micro_version])