Set correct humidity unit to remove log error

[tomrosenback]

Noted that Home Assistant complains about incorrect unit for humidity device class, so corrected it to % instead of %H.

[Jalle19]

Interesting find, thanks!

[Jalle19]

Adding the error message here for posterity:

sensor.eda_exhaustairhumidity (<class 'homeassistant.components.mqtt.sensor.MqttSensor'>) is using native unit of measurement '%H' which is not a valid unit for the device class ('humidity') it is using; expected one of ['%'];