Fix sort methods signature

src/Collections/IImmutableCollection.php

@@ -140,7 +140,7 @@ interface IImmutableCollection extends IteratorAggregate, JsonSerializable, Coun
      *
      * @throws Throwable If an error occurs
      */
-    public function sort (Closure|IComparator|null $sorter = null): self;
+    public function sort (Closure|IComparator|null $sorter = null): static;
     /**
      * Sort the elements by key
      *
@@ -154,7 +154,7 @@ interface IImmutableCollection extends IteratorAggregate, JsonSerializable, Coun
      *
      * @throws Throwable If an error occurs
      */
-    public function sortByKey (Closure|IComparator $sorter): self;
+    public function sortByKey (Closure|IComparator $sorter): static;
 
     /**
      * The list of all keys