remove deprecation notice for Cache::read() and Cache::write(), fixes #3701

Closes #3701

Merge request studip/studip!3203

lib/classes/cache/Cache.php

@@ -97,8 +97,6 @@ abstract class Cache implements CacheItemPoolInterface
      *
      * @return mixed    the previously stored data if an item with such a key
      *                  exists on the server or FALSE on failure.
-     *
-     * @deprecated To be removed with Stud.IP 7.0.
      */
     public function read($arg)
     {
@@ -117,8 +115,6 @@ abstract class Cache implements CacheItemPoolInterface
      * @param int    $expires  the item's expiry time in seconds. Optional, defaults to 12h.
      *
      * @return bool     returns TRUE on success or FALSE on failure.
-
-     * @deprecated To be removed with Stud.IP 7.0.
      */
     public function write($name, $content, $expires = self::DEFAULT_EXPIRATION)
     {