feat: v0.3.7, yubikey is optional

Cargo.toml

@@ -1,10 +1,14 @@
 [package]
 name = "local-mini-kms"
-version = "0.3.6"
+version = "0.3.7"
 edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
+[features]
+default = ["yubikey"]
+yubikey = ["yubico_manager"]
+
 [dependencies]
 zeroize = "1.8"
 clap = "2.34"
@@ -22,7 +26,7 @@ rust_util = { version = "0.6", features = ["use_clap"] }
 tokio = { version = "1.37", features = ["full"] }
 hyper = { version = "0.14", features = ["client", "server", "tcp", "http1", "http2"] }
 rusqlite = "0.31"
-yubico_manager = "0.9"
+yubico_manager = { version = "0.9", optional = true }
 rpassword = "7.3"
 rand = "0.8"