AttributeMap: add phpstan generic parameters for ArrayAccess

src/pocketmine/entity/AttributeMap.php

@@ -25,6 +25,9 @@ namespace pocketmine\entity;
 
 use function array_filter;
 
+/**
+ * @phpstan-implements \ArrayAccess<int, float>
+ */
 class AttributeMap implements \ArrayAccess{
 	/** @var Attribute[] */
 	private $attributes = [];