Update bytes requirement from 0.5 to 0.6

Updates the requirements on [bytes](https://github.com/tokio-rs/bytes) to permit the latest version.
- [Release notes](https://github.com/tokio-rs/bytes/releases)
- [Changelog](https://github.com/tokio-rs/bytes/blob/master/CHANGELOG.md)
- [Commits](https://github.com/tokio-rs/bytes/compare/v0.5.0...v0.6.0)

Signed-off-by: dependabot[bot] <support@github.com>

Cargo.toml

@@ -20,7 +20,7 @@ tls-vendored = ["native-tls", "native-tls/vendored"]
 [dependencies]
 base64 = "0.13.0"
 byteorder = "1.3.2"
-bytes = "0.5"
+bytes = "0.6"
 http = "0.2"
 httparse = "1.3.4"
 input_buffer = "0.3.0"