[!!!][TASK] Raise PHP requirement to 7.0

TYPO3 CMS 8 requires at least PHP 7.0

Change-Id: I9fad64c48270a4ac1122fb28f52da5579d46e629
Resolves: #73655
Releases: master
Reviewed-on: https://review.typo3.org/46878


Reviewed-by: Mathias Schreiber <mathias.schreiber@wmdb.de>
Tested-by: Mathias Schreiber <mathias.schreiber@wmdb.de>
Reviewed-by: Mathias Brodala <mbrodala@pagemachine.de>
Reviewed-by: Frank Naegler <frank.naegler@typo3.org>
Tested-by: Frank Naegler <frank.naegler@typo3.org>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>