Allow symfony security-csrf and asset 5.1

[jordisala1991]

Subject

I am targeting this branch, because this is BC.

Changelog

### Added
- Allow `symfony/security-csrf` and `symfony/asset` ^5.1

[wbloszyk]

@jordisala1991
Could you move this PR to master branch? We can't add support for Symfony5 in Sonata3 becouse Symfony 5 - TODO list

[jordisala1991]

This change does not break bc, so it can be done on 3.x (I will revert the security-core)

[franmomu]

This change does not break bc, so it can be done on 3.x (I will revert the security-core)

Can you please also add symfony/asset 😬 ? https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Asset/CHANGELOG.md apparently there is no problem.

[wbloszyk]

@jordisala1991
I know this is not BC-break. I mean something else. Some symfony bundle must be with symfony version. What is point to add support for 5.x when install it will be imposible? That why I ask about move it to master.

[jordisala1991]

Because people usually do not have all possible symfony dependencies fixed on 4.4 or use flex like this:

    "extra": {
        "symfony": {
            "allow-contrib": true,
            "require": "^4.4 || ^5.1"
        }
    },

So if a package is compatible, I am happy with getting an upgrade. I don't care if I don't have all possible packages upgraded

[franmomu]

Thanks @jordisala1991!