The gauge event uses `actor_id`

[nonowazu]

Describe the bug
The gauge event uses actor_id (type int) as opposed to actor (type Actor) - this means the event is inconsistent with other event(s) that make an actor object.

To Reproduce

• Get a gauge event

Expected behaviour

gauge: Gauge = get_some_gauge_event()
print(gauge.actor) # should work

System (please complete the following information):

• OS: any
• Python version: 3.10+
• nari Version or Commit Reference: latest head (5239902)

Additional context
I'm really documenting this here as something to fix to make the library consistent