Bump min to PHP 7.2

[TomasVotruba]

Closes rectorphp/rector#7068

• PHPStan will go to PHP 7.2 in next 1.5 release with 0.8 % installs on PHP 7.1 - see https://github.com/phpstan/phpstan/releases/tag/1.5.0
• Rector is now used on PHP 7.1 only by 0.2 % - https://packagist.org/packages/rector/rector/php-stats

Time to follow up 📈

[samsonasik]

@TomasVotruba DowngradeParameterTypeWidening settings at build/config/config-downgrade.php seems no longer needed as it down from php 7.2 to 7.1

rector-src/build/config/config-downgrade.php

Lines 30 to 36 in 6ebf140

	$services = $containerConfigurator->services();
	$services->set(DowngradeParameterTypeWideningRector::class)
	->configure([
	LoaderInterface::class => ['load'],
	Loader::class => ['import'],
	]);

[TomasVotruba]

@samsonasik Thanks 👍 I've removed it

[samsonasik]

Phpstan 1.5.0 released https://github.com/phpstan/phpstan/releases/tag/1.5.0

I think requirement need to be updated too composer.json

"phpstan/phpstan": ^1.5.0"

in both root composer.json and target-repository

[TomasVotruba]

@samsonasik Thanks 👍

[TomasVotruba]

Let's try the deploy and test the downgraded version 👍