Merge branch '6.0' into 6.1

* 6.0:
  Use mb_convert_encoding instead of utf8_decode
  [SecurityBundle] Remove forgotten unused code
  Minor @requires function tests cleanup
  [FrameworkBundle] Always add CacheCollectorPass
  Fix "Notice: Undefined index: headers" in messenger with Oracle
  [String] Fix ansi escape sequences regex
  Indicate support for doctrine/persistence 3
  [Routing] fix router base url when default uri has trailing slash
  Replace deprecated String.prototype.substr()

Author: derrabus

Tests/Helper/QuestionHelperTest.php

@@ -714,9 +714,6 @@ public function testNoInteraction()
         $this->assertEquals('not yet', $dialog->ask($this->createStreamableInputInterfaceMock(null, false), $this->createOutputInterface(), $question));
     }
 
-    /**
-     * @requires function mb_strwidth
-     */
     public function testChoiceOutputFormattingQuestionForUtf8Keys()
     {
         $question = 'Lorem ipsum?';