Make the dev-master version compatible with the dev-master version of phpstan

[Gallaecio]

Otherwise, when installing phpstan-laravel along with the dev-mater version of phpstan, you get:

  Problem 1
    - Installation request for weebly/phpstan-laravel dev-master -> satisfiable by weebly/phpstan-laravel[dev-master].
    - weebly/phpstan-laravel dev-master requires phpstan/phpstan ^0.9 -> satisfiable by phpstan/phpstan[0.9, 0.9.1, 0.9.2] but these conflict with your requirements or minimum-stability.

[carusogabriel]

I'd love to see this one ❤️