make regestering server functions optional

packages/fullstack/Cargo.toml

@@ -13,7 +13,7 @@ keywords = ["dom", "ui", "gui", "react", "ssr", "fullstack"]
 
 [dependencies]
 # server functions
-server_fn = { git = "https://github.com/leptos-rs/leptos", rev = "671b1e4a8fff7a2e05bb621ef08e87be2b18ccae", default-features = false, features = ["stable"] }
+server_fn = { git = "https://github.com/leptos-rs/leptos", rev = "15a4e54435eb5a539afb75891292bcccd2cc8e85", default-features = false, features = ["stable"] }
 dioxus_server_macro = { path = "server-macro" }
 
 # warp