prevent php8 deprecation warnings, fixes #2287

Closes #2287

Merge request studip/studip!1510

lib/phplib/CT_Cache.class.php

@@ -25,7 +25,7 @@ class CT_Cache {
         return $this->ac_get_value($str) === false ? $str : false;
     }
 
-    function ac_store($id, $name = null, $str) {
+    function ac_store($id, $name, $str) {
         $cache_key = self::CACHE_KEY_PREFIX . '/' . $id;
         return $this->cache->write($cache_key, $str, self::SESSION_LIFETIME);
     }
@@ -51,7 +51,6 @@ class CT_Cache {
     function ac_get_changed($id, $name = null) {
     }
 
-    function ac_set_changed($id, $name = null, $timestamp) {
+    function ac_set_changed($id, $name, $timestamp) {
     }
 }
-?>

lib/phplib/CT_Sql.class.php

@@ -79,7 +79,7 @@ class CT_Sql {
         return $rs->fetchColumn();
     }
     
-    function ac_set_changed($id, $name = null, $timestamp){
+    function ac_set_changed($id, $name, $timestamp){
         $db = DBManager::get();
         $stmt = $db->prepare(sprintf("UPDATE %s SET changed = FROM_UNIXTIME(?) WHERE sid  = ?", $this->database_table));
         $stmt->execute([$timestamp, $id]);
@@ -99,4 +99,3 @@ class CT_Sql {
     function ac_halt($s) {
     }
 }
-?>