Allow Symfony 7 Components

Allow Symfony 7 Components (Case 169220) (#17)

- Disallow PHP < 7.0 as we use return types from now.

Provide compatibility with Symfony 6.x

2.2.0

Provide compatibility with Symfony 6.x (#16)

Resolve some deprecation notices (#15)

Add some return type hints (#15)

This PR adds return type hints to resolve deprecation warnings issued by Symfony's DebugClassLoader in Symfony 5.4.

In places where we cannot reasonably rule out that methods have been overridden, only soft (docblock-based) types are added. 

In case you have overwritten these methods, you should start adding _real_ return type declarations _now_.

Compatibility with Symfony 5.x

This release changes constraints so this bundle can be installed with Symfony 5.x.

Fixes additional Symfony deprecation notices

See the UPGRADING file for details about the Filter interface that had to be changed.

Fixe Symfony 4.2-Deprecation

https://webfactory.fogbugz.com/f/cases/98936/Passe-TreeBuilder-Benutzung-in-Symfony-Projekten-an-aktuelle-Schnittstelle-an

Enables Symfony 3.3+ Autowiring

1.8.0

Leverage Symfony 3.3+ Autowiring

Allows installation together with Syfony 3.4 and 4.x

This has not undergone careful testing in the wild, so report back in #11 if it works for you.

Fixed a Twig deprecation notice

1.3.4

Fix Twig deprecation notice by implementing Twig_Extension_GlobalsInt…

Fixes a Symfony deprecation notice

1.3.3

Fix Symfony deprecation notice