Add Symfony 8 support

[Kocal]

This PR increase version constraints on symfony/* packages to allow Symfony 8, which will be released this month

[Kocal]

I'm passing the PR in draft, Behat will surely draft a new major release for Symfony 8: Behat/Behat#1687 (review)

Thus, some additional work will be required here

[Fahani]

Hello @Kocal , do you have any update on when compatibility with Symfony 8 will be added?

[Kocal]

Hi, I didn't have so much time recently due to the SymfonyCon. Support for Symfony 8 will land in Behat 4, so there is still more work to do here

[Fahani]

Totally understandable, thanks for the feedback!

[mpdude]

Maybe we should re-label this as "declare compatibility with Symfony 8 components"?

As far as this extension here is concerned, the relevant interface changes that might make it necessary to create a Behat 4 release have already been adressed.

So, from the POV of this package here, the change is sound. We can say "we're compatible with Behat 3 and Symfony 8", so we should get this merged (+ released).

Depending on what Behat comes up with for a 4.x release, we can either address those changes later, separately, or just update the dependency declaration to say "oh, and Behat ^4.0 is fine, too". But that does not have to stop us here.