Ensure blocking read call is done outside event loop

[dknowles2]

To fix warnings such as:

2024-10-05 16:39:40.112 WARNING (MainThread) [homeassistant.util.loop] Detected blocking call to read_text with args (PosixPath('/usr/local/lib/python3.12/site-packages/pytboss/grills.json'),) inside the event loop by custom integration 'pitboss' at custom_components/pitboss/config_flow.py, line 58: models = [g.name for g in grills.get_grills(control_board=control_board)] (offender: /usr/local/lib/python3.12/site-packages/pytboss/grills.py, line 295: grills_json = resources.files(__package__).joinpath("grills.json").read_text()), please create a bug report at https://github.com/dknowles2/ha-pitboss/issues