Bump the vulnerable dependencies

All bump up includes minor updates. I checked this using cargo-audit.

Updated dependencies:

* http 0.1.17 -> 0.1.21
* hyper 0.12.19 -> 0.12.35
* smallvec 0.6.4 -> 0.6.13
* libflate 0.1.23 -> 0.1.27
* spin 0.5.0 -> 0.5.2
* yaml-rust: This commit updates clap instead. clap 2.33 does not
affected by the problem.

Links about the security advisories

* https://rustsec.org/advisories/RUSTSEC-2019-0034
* https://rustsec.org/advisories/RUSTSEC-2019-0033
* https://rustsec.org/advisories/RUSTSEC-2020-0008
* https://rustsec.org/advisories/RUSTSEC-2019-0010
* https://rustsec.org/advisories/RUSTSEC-2019-0012
* https://rustsec.org/advisories/RUSTSEC-2019-0013
* https://rustsec.org/advisories/RUSTSEC-2018-0006

Author: majecty