feat: allow symfony 7

[shyim]

Q	A
Bug fix?	yes
New feature?	no
BC breaks?	no
Deprecations?	no
Related tickets	testcontainers/testcontainers-php#33
Documentation	if this is a new feature, link to pull request in https://github.com/php-http/documentation that adds relevant documentation
License	MIT

What's in this PR?

Allow usage of Symfony 7

Why?

Which problem does the PR fix? (remove this section if you linked an issue above)

Example Usage

// If you added new features, show examples of how to use them here
// (remove this section if not a new feature)

$foo = new Foo();

// Now we can do
$foo->doSomething();

Checklist

• Updated CHANGELOG.md to describe BC breaks / deprecations | new feature | bugfix
• Documentation pull request created (if not simply a bugfix)

To Do

• If the PR is not complete but you want to discuss the approach, list what remains to be done here