✨ Support extra DHT sensor

[jerr0328]

Support for popular DHT11/DHT22 sensor to augment the CO2 sensors, especially if the CO2 sensor doesn't have a built-in humidity sensor.

[jerr0328]

Some notes while testing this:

• sigterm isn't actually terminating anymore, probably the homekit asyncio loop needs to be terminated as well?
• Should probably refactor the co2 module.
• Lots of errors when fetching temperature/humidity from the sensor. This is a known issue for DHT11/DHT22, will likely need to lower the log severity and not log a stacktrace to reduce log spam.
• When upgrading to this version, need to remove and re-add the two homekit accessories.
• DHT temperature (for me at least) is 2C higher than what the CO2 sensor reads.
• Should add more optional labels for Prometheus to help organize/filter

For the overall problem with DHT sensors on a full Linux system, options are to either go with a I2C sensor or put a microcontroller in front of it. I have one ESP8266 with a DHT11/DHT22 (I can't remember exactly which) sensor pushing to prometheus push gateway, though I might change that to MQTT if I get more and unify the code (or have it run a prometheus web server and scrape it)