Upgrade hyper for security

[tirkarthi]

Hi,

It seems the project uses a version of hyper that is vulnerable to attacks. Please find the advisory as below :

Advisory : https://github.com/RustSec/advisory-db/blob/master/Advisories.toml#L18
Wiki : https://github.com/hyperium/hyper/wiki/Security-001
Commit : hyperium/hyper@39ef635

Please consider adding cargo-audit to the CI to get notified in the future. Feel free to close this issue if it has been fixed or irrelevant since this was filed with the help of data from crates.io .

Thanks