[mutter] build: Update Wayland dependency to 1.21

[Marge Bot <marge-bot src gnome org>]

commit 80db59153453071de6c3db3507f462d59cbb8ec4
Author: Carlos Garnacho <carlosg gnome org>
Date:   Thu Jul 14 22:22:47 2022 +0200

    build: Update Wayland dependency to 1.21
    
    This is needed for wl_seat v8.
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1962>

 meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index 11af911f23..60936dd68b 100644
--- a/meson.build
+++ b/meson.build
@@ -40,7 +40,7 @@ udev_req = '>= 228'
 gudev_req = '>= 232'
 
 # wayland version requirements
-wayland_server_req = '>= 1.20'
+wayland_server_req = '>= 1.21'
 wayland_protocols_req = '>= 1.25'
 
 # native backend version requirements