Add support for Symfony 7

[alexander-schranz]

Q	A
Bug fix?	no
New feature?	no
BC breaks?	no
Deprecations?	no
Fixed tickets	parts of https://github.com/sulu/sulu/issues/7413
Related issues/PRs	https://github.com/Sylius/SyliusThemeBundle/pull/131, https://github.com/Sylius/SyliusThemeBundle/pull/134
License	MIT

What's in this PR?

Add support for Symfony 7.

Why?

See https://github.com/sulu/sulu/issues/7413

[Prokyonn]

@alexander-schranz ~symfony/proxy-manager-bridge is still v6.4.8~

edit: nvm the package is abandoned and not required anymore after 6.4

linting still fails

[alexander-schranz]

@Prokyonn for symfony/proxy-manager-bridge we can remove it as soon as we minimal require Symfony 6.2 in sulu/sulu: https://github.com/symfony/symfony/pull/54629

[alexander-schranz]

The failing lint task is unrelated to us and need to be fixed in https://github.com/Sylius/SyliusThemeBundle/pull/134