[TASK] Update PHPUnit to version 5.4

The warnings for "getMock()" will be taken care of in a separate
change.

Change-Id: I493d6a2fdf0c9eb98f468afe11e4cceb62fa57e9
Resolves: #76673
Releases: master
Reviewed-on: https://review.typo3.org/48596


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Elmar Hinz <t3elmar@gmail.com>
Tested-by: Elmar Hinz <t3elmar@gmail.com>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Tested-by: Andreas Fernandez <typo3@scripting-base.de>