Make dependency doctrine/annotations optional

[W0rma]

Since #326 native PHP attributes can be used for configuration.

When using PHP 8.1 or greater PHP attributes can fully replace Doctrine annotations.

Thus, we could think about making the doctrine/annotations dependency optional (see #326 (comment)).

[W0rma]

Making the annotations package optional is a BC break because packages which use Doctrine annotations for configuration would need to install doctrine/annotations explicitly.

In jms/serializer a similar change was released in a minor release (schmittjoh/serializer#1471).

@goetas Should we use a similar strategy for willdurand/hateoas or would you prefer to work on that for the next major release (which could maybe even drop annotations completely while raising the minimum required PHP version to 8.1)?

[goetas]

I'm fine in doing something as in jms serializer. a small bc break but it allows us to move forward.
for sure some people will complain, but i will be happier without having to worry about it for the next years :)