Upgrade to using Litestream `v0.5`

[epompeii]

https://fly.io/blog/litestream-v050-is-here/

They are actually actively developing litestream again, so check for the latest here: https://github.com/benbjohnson/litestream/releases

This will require changing the replicas array in the server config to a replica object as v0.5.0 drops support for multiple replicas