tracking broken PHP-8 dependencies that cause CI to fail

[jrushlow]

This issue is for tracking the progress of PHP 8 compatability for php-cs-fixer, twigcs & other blockers for CI

• Twig CS Issue:
  PHP 8 support friendsoftwig/twigcs#151

• PHP CS Fixer Issue:
  PHP 8.0 support PHP-CS-Fixer/PHP-CS-Fixer#4702

• DoctrineMigrationsBundle
  php 8 doctrine/DoctrineMigrationsBundle#383

When both support PHP8 - we'll need to re-evaluate and/or walk back PR #724 which skips cs related tests in PHP 8

[jrushlow]

Install of php-cs-fixer is now possible on PHP 8 since version 2.17 - PHP-CS-Fixer/PHP-CS-Fixer#4702 (comment)

[jrushlow]

TwigCS v5 has been released.