Updating to miscreant 0.4.0-beta for stable support

Cargo.toml

@@ -20,7 +20,7 @@ serde_derive = "1.0"
 
 [dev-dependencies]
 serde_json = "1.0"
-miscreant = "0.3"
+miscreant = { version = "0.4.0-beta", features = ["aes-soft"] }
 rmp-serde = "0.13.7"
 bincode = "1.0"
 serde_cbor = "0.8"