As decided by core team leader, PHP minimum version
requirement for core version 9.0 is 7.2.0.

The patch sets this in root composer.json, together
with config.platform.php, and adapts sysext/core/composer.json.

Resolves: #83290
Related: #83289
Releases: master
Change-Id: I813d0a2b69005c84ba5dedb45b3d4bd0388e43d8
Reviewed-on: https://review.typo3.org/55035


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Tested-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Reviewed-by: Susanne Moog <susanne.moog@typo3.org>
Tested-by: Susanne Moog <susanne.moog@typo3.org>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>