Update phpunit/phpunit requirement from ^4.8 || ^5.0 || ^6.0 || ^7.0 || ^8.0 || ^9.0 || ^10.0 to ^4.8 || ^5.0 || ^6.0 || ^7.0 || ^8.0 || ^9.0 || ^10.0 || ^11.0

Update phpunit/phpunit requirement from ^4.8 || ^5.0 || ^6.0 || ^7.0 || ^8.0 || ^9.0 || ^10.0 to ^4.8 || ^5.0 || ^6.0 || ^7.0 || ^8.0 || ^9.0 || ^10.0 || ^11.0 #60