drop md5 crate dependency

we already depend on openssl which also provides md5

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

Cargo.toml

@@ -22,7 +22,6 @@ hyper = { version = "0.13.0-alpha.1" }
 lazy_static = "1.3"
 libc = "0.2"
 log = "0.4"
-md5 = "0.6"
 mio = "0.6"
 native-tls = "0.2"
 nix = "0.15"