refactor: add native return type for deleteMatching in CacheInterface

Author: yassinedoghri

system/Cache/CacheInterface.php

@@ -55,10 +55,10 @@ public function delete(string $key);
      * Deletes items from the cache store matching a given pattern.
      *
      * @param string $pattern Cache items glob-style pattern
-     *
-     * @return int
+     * 
+     * @return int Number of deleted items
      */
-    public function deleteMatching(string $pattern);
+    public function deleteMatching(string $pattern): int;
 
     /**
      * Performs atomic incrementation of a raw stored value.