Add support for the missing tagged_builds parameter in the Actor update method, allowing users to create, update, or remove build tags.

The parameter accepts a dictionary mapping tag names to either:

• A dict with 'build_id' key to assign/reassign a tag
• None to remove a tag

Example usage:

client.actor('my-actor').update(
    tagged_builds={
        'latest': {'build_id': 'abc123'},
        'beta': None  # removes beta tag
    }
)

Changes:

• Added tagged_builds parameter to get_actor_representation() helper function
• Added tagged_builds parameter to ActorClient.update() (sync version)
• Added tagged_builds parameter to ActorClientAsync.update() (async version)

Related:

• Related JS client issue: Add missing taggedBuild parameter to actor update type apify-client-js#829

Closes #585