Rider 18 rates

[mutilator]

can you also pull in rates from https://www.dteenergy.com/content/dam/dteenergy/deg/website/hybris/rooftop-solar/Rider18Calculator.xlsx

for export calculations

[javaDevJT]

https://github.com/javaDevJT/DTE-Rates-for-Home-Assistant/releases/tag/v2.0.5