Remove data type mixed. Considered annotations for php7.4.

DataStructures/DisjointSets/DisjointSetNode.php

@@ -8,7 +8,7 @@ class DisjointSetNode
      * @var int|string|float|null
      */
     // PHP7.4: Defined with annotations
-    public $data;       # replace with type hint "mixed" as for PHP 8.0^.
+    public $data;       # replace with type hint "mixed" as of PHP 8.0^.
     public int $rank;
     public DisjointSetNode $parent;