Upgrade hashbrown to 0.16 (#608)

Author: djc

Cargo.lock

@@ -30,7 +30,7 @@ crossbeam-epoch = { version = "0.9", default-features = false }
 crossbeam-queue = { version = "0.3", default-features = false, features = ["std"] }
 crossbeam-utils = { version = "0.8", default-features = false }
 getopts = { version = "0.2", default-features = false }
-hashbrown = { version = "0.15", default-features = false, features = ["default-hasher", "raw-entry"] }
+hashbrown = { version = "0.16", default-features = false, features = ["default-hasher", "raw-entry"] }
 hdrhistogram = { version = "7.2", default-features = false }
 http-body-util = { version = "0.1", default-features = false }
 hyper = { version = "1.1", default-features = false, features = ["server", "client"] }