Use head elements and new manganis syntax in examples (#2688)

* use head elements and new manganis syntax in examples
* only enable desktop workspace example scraping during a dioxus release

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Co-authored-by: Jonathan Kelley <jkelleyrtp@gmail.com>

examples/custom_assets.rs

@@ -11,8 +11,7 @@ use dioxus::prelude::*;
 static ASSET_PATH: &str = "examples/assets/logo.png";
 
 #[cfg(feature = "collect-assets")]
-static ASSET_PATH: &str =
-    manganis::mg!(image("examples/assets/logo.png").format(ImageType::Avif)).path();
+static ASSET_PATH: &str = asset!("examples/assets/logo.png".format(ImageType::Avif));
 
 fn main() {
     launch(app);