Add trailing newline to graph's node labels

[spagh-eddie]

Fixes #582

I tested this with combinations: on_enter, on_enter+on_exit, timeout+on_timeout, and on_enter+timeout+on_timeout

states = [
    {
        "name": "initial",
        "on_enter": ["this is odd", "see?"],
        "on_exit": ["this is odd", "see?"],
        "timeout": 30,
        "on_timeout": ["do_something", "do_something"],
    }
]