[BUGFIX] Raise required PCRE version

Warn about an outdated PCRE version which is not compatible to PHP 7.0
in the Install Tool to make aware of possible PHP crashes in the TYPO3
backend.

Releases: master, 8.7
Resolves: #81335
Change-Id: I0db145146eb02bcab81a83195f375c87ae85f3e4
Reviewed-on: https://review.typo3.org/52936


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>