[TwigBundle] update required minimum TwigBridge version

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | 
| License       | MIT
| Doc PR        | 

To be able to use `Twig_SimpleFunction` in `AssetsExtension`, Twig has
to be present in version 1.12 or higher. The TwigBridge only enforces
this Twig version as of version 2.3.10.