Bump serdect dependency to v0.3 (#719)

NOTE: this release includes breaking changes to the wire format.
See RustCrypto/formats#1631

Author: scv35

Cargo.lock

@@ -25,7 +25,7 @@ hybrid-array = { version = "0.2", optional = true }
 num-traits = { version = "0.2.19", default-features = false }
 rand_core = { version = "0.6.4", optional = true }
 rlp = { version = "0.6", optional = true, default-features = false }
-serdect = { version = "0.3.0-rc.0", optional = true, default-features = false }
+serdect = { version = "0.3", optional = true, default-features = false }
 zeroize = { version = "1", optional = true, default-features = false }
 
 [dev-dependencies]