[gimp] app: this string became singular. Fix the grammar.

[Jehan <jehanp src gnome org>]

commit 27ca25f15a8214d3e9384512fa198984ccad8179
Author: Jehan <jehan girinstud io>
Date:   Tue Feb 15 23:52:08 2022 +0100

    app: this string became singular. Fix the grammar.
    
    Thanks to Anders Jonsson for notifying the bug.

 app/tools/gimpmovetool.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/app/tools/gimpmovetool.c b/app/tools/gimpmovetool.c
index 71a16c35a9..aa5ddefcf4 100644
--- a/app/tools/gimpmovetool.c
+++ b/app/tools/gimpmovetool.c
@@ -363,7 +363,7 @@ gimp_move_tool_button_press (GimpTool            *tool,
 
             for (iter = selected_items; iter; iter = iter->next)
               if (gimp_item_is_position_locked (iter->data, &locked_item))
-              locked_message = _("A selected layers' position is locked.");
+              locked_message = _("A selected layer's position is locked.");
           }
       }
       break;