Fix injectivity type

stdlib/map.mli

@@ -67,7 +67,7 @@ module type S =
     type key
     (** The type of the map keys. *)
 
-    and (!+'a) t
+    type !+'a t
     (** The type of maps from type [key] to type ['a]. *)
 
     val empty: 'a t

stdlib/moreLabels.mli

@@ -571,7 +571,7 @@ module type S =
     type key
     (** The type of the map keys. *)
 
-    and (!+'a) t
+    type !+'a t
     (** The type of maps from type [key] to type ['a]. *)
 
     val empty: 'a t

stdlib/templates/map.template.mli

@@ -67,7 +67,7 @@ module type S =
     type key
     (** The type of the map keys. *)
 
-    and (!+'a) t
+    type !+'a t
     (** The type of maps from type [key] to type ['a]. *)
 
     val empty: 'a t