[mutter] boxes: Fix grammar in warning

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

commit 5f78e932a891c7e32b050687ab69d6f70883afd6
Author: Björn Daase <bjoern daase net>
Date:   Fri Jan 14 19:12:02 2022 +0100

    boxes: Fix grammar in warning
    
    Spotted while debugging https://gitlab.gnome.org/GNOME/mutter/-/issues/64
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2236>

 src/core/boxes.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/core/boxes.c b/src/core/boxes.c
index f235f98677..f4ec5408ae 100644
--- a/src/core/boxes.c
+++ b/src/core/boxes.c
@@ -434,7 +434,7 @@ merge_spanning_rects_in_region (GList *region)
 
   if (region == NULL)
     {
-      g_warning ("Region to merge was empty! Either you have a some "
+      g_warning ("Region to merge was empty! Either you have some "
                  "pathological STRUT list or there's a bug somewhere!");
       return NULL;
     }