Support for !secret in apps.yaml

[markbw999]

Hi Trefor, since your great support for Solcast in predbat I now have to paste my solcast api directly into apps.yaml. For all other types of system specific info in my HA configuration I like to group them in secrets.yaml. I tried setting this up but predbat doesn't like !secret in apps.yaml. Is it possible to provide support for this feature? Thanks, Mark