Bump version to 1.1.91
diff --git a/configure.ac b/configure.ac
index 72ab1f9..82e55e4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2,7 +2,7 @@
 
 m4_define([wayland_major_version], [1])
 m4_define([wayland_minor_version], [1])
-m4_define([wayland_micro_version], [90])
+m4_define([wayland_micro_version], [91])
 m4_define([wayland_version],
           [wayland_major_version.wayland_minor_version.wayland_micro_version])