Implement Tarallo.update_features

[lvps]

Here's an example:

session.patch(f"http://127.0.0.1:8080/v1/items/{code}/features", headers={"Content-Type": "application/json"}, data=json.dumps({'psu-rails-most-power': '5v'}))

The data is a dictionary of feature names mapped to values (or None if you want to delete that feature). The "difficult" part will be to obtain this "delta" of changes from an Item.

[lvps]

Done in https://github.com/WEEE-Open/python-tarallo/commit/08356dce64f8c7595e8bf12cc58e20f8b74dd3a0 and previous commits