LoRaGpio: method monitor_continuous(...) not implemented

[wke67]

The current code on github is a major improvement compared to the pypi.org release version 1.4.0. since it gets rid of the RPIO.GPIO which depends on gpiod <2.0.0!!
When running the LoRaRF.request(LoRa.RX_CONTINUOUS) it turns out, that the method LoRaGpio.monitor_continuous(...) is not implemented. The fix is simple: install the github version (editable) and add the method to class LoRaGpio (base.py)

def monitor_continuous(self, callback, timeout: float):
    while True:
        self.monitor(callback, timeout)