Misleading docs re: CallbackAPIVersion

[rittneje]

The docstring for the paho.mqtt.client.Client constructor currently states:

paho.mqtt.python/src/paho/mqtt/client.py

Lines 649 to 652 in af64a43

	:param CallbackAPIVersion callback_api_version: define the API version for user-callback (on_connect, on_publish,...).
	This field is required and it's recommended to use the latest version (CallbackAPIVersion.API_VERSION2).
	See each callback for description of API for each version. The file docs/migrations.rst contains details on
	how to migrate between version.

However, this is not true. This parameter is not required and defaults to VERSION1.

paho.mqtt.python/src/paho/mqtt/client.py

Line 735 in af64a43

callback_api_version: CallbackAPIVersion = CallbackAPIVersion.VERSION1,

The docstring is also wrong because it has the wrong constant for the CallbackAPIVersion enum.

The migration guide also does not make this situation particularly clear.