Update sensor.py with state_class_total_increasing

[grisu122]

Energie counters need to be state_class total_increasing to be configured in homeassistants energy dashboard. source is this post: https://community.home-assistant.io/t/help-with-esphome-and-energy-devices-not-available-in-energy-dashboard/337607

[andyboeh]

Looks good to me, thanks