graph: Remove unused dependency humantime

Author: lutter

Cargo.lock

@@ -37,7 +37,6 @@ hyper-util = { version = "0.1", features = ["full"] }
 futures01 = { package = "futures", version = "0.1.31" }
 lru_time_cache = "0.11"
 graphql-parser = "0.4.1"
-humantime = "2.3.0"
 lazy_static = "1.5.0"
 num-bigint = { version = "=0.2.6", features = ["serde"] }
 num-integer = { version = "=0.1.46" }