[TASK] bamboo v7: Include php 7.2 in test suite

Run core v7 acceptance, unit and lint tests on php 7.2, too.

Change-Id: I2db7c3fb6cde92c6d2d0320ba39343679e57e126
Resolves: #83215
Releases: 7.6
Reviewed-on: https://review.typo3.org/54928


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>