Update to be compatible with CakePHP 3.5

[PhantomWatson]

Currently, this package's version constraint for PHPUnit (4.*) allows for CakePHP 3.4.1 but not any newer versions, as CakePHP 3.4.2 requires PHPUnit >=5.7.

[om1]

If anyone searchs for an updated version check out this package:

https://packagist.org/packages/rubyan/cake3-cookieauth