chore: add feature for enabling serializing keycodes

Cargo.toml

@@ -15,6 +15,8 @@ animated-image = ["image", "dep:async-fs", "tokio?/io-util", "tokio?/fs"]
 debug = ["iced/debug"]
 # Enables pipewire support in ashpd, if ashpd is enabled
 pipewire = ["ashpd?/pipewire"]
+# Enables keycode serialization
+serde-keycode = ["iced_core/serde"]
 # smol async runtime
 smol = ["iced/smol"]
 # Tokio async runtime
@@ -133,4 +135,4 @@ exclude = ["examples/design-demo", "iced"]
 libcosmic = { path = "./" }
 
 # [patch."https://github.com/pop-os/cosmic-time"]
-# cosmic-time = { path = "../cosmic-time" }
+# cosmic-time = { path = "../cosmic-time" }