Cleaned up dependencies

Cargo.toml

@@ -4,7 +4,7 @@ version = "0.0.1"
 authors = ["Luciano Mammino"]
 edition = "2018"
 description = "A parser and validator for the EU Digital Green Certificate (dgc) a.k.a. greenpass"
-keywords = ["dgc", "greenpass", "digital green certificate", "cose", "health"]
+keywords = ["dgc", "greenpass", "certificate", "cose", "health"]
 categories = ["encoding", "data-structures", "cryptography"]
 repository = "https://github.com/lmammino/dgc"
 readme = "README.md"
@@ -22,7 +22,6 @@ lazy_static = "1.4.0"
 ring-compat = "0.3.2"
 serde = "1.0.130"
 serde_json = "1.0.64"
-serde-transcode = "1.1.0"
 thiserror = "1.0.30"
 x509-parser = "0.12.0"