Allow dangling commas in annotations

This is a very simple change; I hoped we can get rid of the whole of Doctrine Commons but as we use Reflection, we can't alas. Still, for easier review, attached is the composer.json change separately. The patch contains the results of composer update doctrine/annotations.

The relevant grammar was:

Annotation     ::= "@" AnnotationName ["(" [Values] ")"]
Values ::= Array | Value {"," Value}*

Now we have

Annotation     ::= "@" AnnotationName MethodCall
MethodCall ::= ["(" [Values] ")"]
Values ::= Array | Value {"," Value}* [","]