[gnome-shell] meson.build: Bump compatible mutter API version to 4

[Jonas Ådahl <jadahl src gnome org>]

commit 264050742b59d92dd530c75186c1e8c806270eee
Author: Jonas Ådahl <jadahl gmail com>
Date:   Fri Nov 23 14:46:51 2018 +0100

    meson.build: Bump compatible mutter API version to 4

 meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index 7a7ae6ab1..6c6321555 100644
--- a/meson.build
+++ b/meson.build
@@ -6,7 +6,7 @@ project('gnome-shell', 'c',
 
 # We depend on a specific version of the libmutter API. The mutter variants of
 # the Cogl and Clutter libraries also use this API version.
-mutter_api_version = '3'
+mutter_api_version = '4'
 
 clutter_pc = 'mutter-clutter-' + mutter_api_version
 cogl_pc = 'mutter-cogl-' + mutter_api_version