Upgrade hex

Cargo.lock

@@ -1646,9 +1646,9 @@ 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 = "hkdf"

plume-common/Cargo.toml

@@ -11,7 +11,7 @@ activitystreams-traits = "0.1.0"
 array_tool = "1.0"
 base64 = "0.13"
 heck = "0.3.0"
-hex = "0.3"
+hex = "0.4"
 hyper = "0.12.33"
 openssl = "0.10.22"
 rocket = "0.4.6"