build(deps): bump hex from 0.3 to 0.4 (#1364)

Author: olix0r

Cargo.lock

@@ -385,9 +385,9 @@ dependencies = [
 
 [[package]]
 name = "hex"
-version = "0.3.2"
+version = "0.4.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "805026a5d0141ffc30abb3be3173848ad46a1b1664fe632428479619a3644d77"
+checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"
 
 [[package]]
 name = "hostname"

linkerd/trace-context/Cargo.toml

@@ -10,7 +10,7 @@ publish = false
 base64 = "0.13"
 bytes = "1"
 futures = { version = "0.3", default-features = false }
-hex = "0.3.2"
+hex = "0.4"
 http = "0.2"
 linkerd-error = { path = "../error" }
 linkerd-stack = { path = "../stack" }