serialize Keypair using tokenator

Signed-off-by: kernelkind <kernelkind@gmail.com>

crates/notedeck/Cargo.toml

@@ -31,6 +31,7 @@ bincode = { workspace = true }
 ehttp = {workspace = true }
 mime_guess = { workspace = true }
 egui-winit = { workspace = true }
+tokenator = { workspace = true }
 
 [dev-dependencies]
 tempfile = { workspace = true }