Fix hydration with empty spread attributes (#4647)

* Fix hydration of empty spread attributes

* add a regression test

* fix doctest

packages/playwright-tests/fullstack-spread/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "dioxus-playwright-fullstack-spread-test"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+dioxus = { workspace = true, features = ["fullstack"] }
+
+[features]
+default = []
+server = ["dioxus/server"]
+web = ["dioxus/web"]