Rusoto 0.47.0

0.47.0 - 2021-06-29

• Update to botocore 1.20.102
• Update to serde_urlencoded 0.7
• Update to rustc_version 0.4
• Update to shlex 1.0
• Update to hmac 0.4
• Replace time-related types in rusoto_signature with chrono types, to
  match rusoto_credential
• Swap the non-RustCrypto md5 crate for the RustCrypto md-5 crate, to match
  usage of RustCrypto sha2 crate
• Remove Sync constraint on ByteStream-related functions.
• Update incorrect minimum versions of async-trait, percent-encoding, and
  serde
• Avoid unnecessary calls to to_string
• Remove unpublished and outdated helpers crate