consider switching from tiny_http

[brayniac]

tiny_http is being flagged for having an open rustsec advisory:

error: 1 vulnerability found!
ID:       RUSTSEC-2020-0000
Crate:    tiny_http
Version:  0.6.2
Date:     2020-06-16
URL:      https://rustsec.org/advisories/RUSTSEC-2020-0000
Title:    HTTP Request smuggling through malformed Transfer Encoding headers
Solution:  No safe upgrade is available!
Dependency tree: 
tiny_http 0.6.2
└── rezolus 2.6.1-alpha.0

It doesn't look like this exposes us to any issues - but we can probably consolidate some dependencies by switching to warp as we already use reqwest which shares a depdency on hyper