[BUG] - Build failed due to default features on rustls

[aawsome]

Description

rustls decided to switch defaults to aws-lc-sys which breaks building on some platforms (or at least needs increased build dependencies)

Can you please consider using ringfor rustls as suppaftp default instead? Maybe add a feature flag for rustls defaults. Thanks a lot!

[aawsome]

For more context: We use suppaftp via openDAL in https://github.com/rustic-rs/rustic_core.