This will be the last PHP requirement upgrade for a while, at least
until stable (and therefore until the next major release).
We have decided to do this now, for the following reasons:
- We want to support MariaDB (and the compatible release of
doctrine/dbal requires 7.1 as well).
- We prefer to upgrade to Laravel 5.6 sooner rather than later.
- Using the PSR-15 middleware standard is easier this way, as we do
not have to switch from zend-stratigility to another PSR-15
implementation. (Stratigility v3, which implements the final
standard, requires 7.1.)