Switch from .toml to .yml

[cellulosa]

hi there and thank you for the great project! One suggestion I have is to switch from .toml to .yml so that environmental variables (e.g. ${PASSWORD}) could be used in the file rather than having plain passwords.

[JohnDoee]

I use this with e.g. docker myself so it is not something I haven't seen before.

With that said, I don't think this is related to yaml at all or a default feature in any way. The task to support ${} is to implement it myself. That also means it is just as much work to do it with toml as yaml.

My test was with pyyaml and that one does not seem to support it in any way.