mb_* functions with BC

tests/Monolog/Handler/TelegramBotHandlerTest.php

@@ -1,4 +1,13 @@
-<?php
+<?php declare(strict_types=1);
+
+/*
+ * This file is part of the Monolog package.
+ *
+ * (c) Jordi Boggiano <j.boggiano@seld.be>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
 
 namespace Monolog\Handler;
 
@@ -39,4 +48,4 @@ class TelegramBotHandlerTest extends TestCase
             ->method('send')
             ->willReturn(null);
     }
-}
+}