Revert "Locked Codeception versions since master is under heavy refactoring"

This reverts commit 7145b9e9a7da9eddfbdc0d7dc6e7eea2a9051371.
Fixes #1412: `FileValidator` still triggers `uploadRequired` error in some case when `skipOnEmpty` is true and no upload is provided
Merge branch 'master' of git://github.com/yiisoft/yii2