Add js feature for getrandom

This is in line with the recommendation in https://docs.rs/getrandom/latest/getrandom/#webassembly-support. We don't know exactly what broke, but this seems like a reasonable fix.

examples/with_winit/Cargo.toml

@@ -47,3 +47,4 @@ console_error_panic_hook = "0.1.7"
 console_log = "1"
 wasm-bindgen-futures = "0.4.33"
 web-sys = { version = "0.3.60", features = [ "HtmlCollection", "Text" ] }
+getrandom = { version = "0.2.10", features = ["js"] }