Migrate off Rusoto

[daviddrysdale]

As per RUSTSEC-2022-0071

The maintainers of Rusoto advise that all its crates are deprecated. This includes the common crates rusoto_core, rusoto_signature, rusoto_credential, and service crates such as rusoto_s3 and rusoto_ec2.

Users should migrate to the AWS SDK for Rust, which is maintained by AWS.