Symfony 6 Compatibility

[mbabker]

This is the work needed for Symfony 6 compatibility. The gist of the changes are:

• Allow Symfony 6 install
• Tweak the GitHub actions config, the tested versions are now set in a matrix so there's only one build config instead of duplicating it for each build
• Drops Symfony 5.3 support, the return signature change in Symfony\Component\Security\Http\Authenticator\AuthenticatorInterface::authenticate() between 5.3 and 5.4 is a bit tricky to deal with while keeping support for the non-LTS 5.3
• Updates Lexik\Bundle\JWTAuthenticationBundle\DependencyInjection\Security\Factory\JWTAuthenticatorFactory to address the security listener factory -> authenticator factory changes/deprecations in the SecurityBundle in 5.4
• Adds typehints or doc blocks as needed

[mbabker]

The compat layer here basically allows the user token class to be usable without the security-guard component.

[chalasr]

🙏 Thanks a lot for working on this!

Given the diff on the public API is quite small, I think we can afford the added typehints without releasing a new major.
About the Response::setData(): static, I fear we have to use the same eval() trick that you removed in ForwardCompatTestCaseTrait. Ok for you?

[mbabker]

I fear we have to use the same eval() trick that you removed in ForwardCompatTestCaseTrait. Ok for you?

Yeah, that would probably work out best. I can mess with that later on.

[chalasr]

Thanks a lot, @mbabker.