Update composer.json to support Symfony 8

[luigif]

In composer.json most symfony dependencies have been updated to support version 8 but the framework bundle was still limited to 7

[ThomasLandauer]

Looks like I missed that in #369 ;-)
But what's the point of having require and require-dev here at all? I mean, Psalm is for development use only, so what does require mean?

Unfortunately, I think that Symfony 8 is not going to work, due to #372