"not all trait items implemented" rust error when running yarn run build

[ducks]

Howdy,

I cloned the repo, ran yarn install and then yarn run build and received the following rust error:

error[E0046]: not all trait items implemented, missing: `change`
  --> src/app.rs:46:1
   |
46 | impl Component for App {
   | ^^^^^^^^^^^^^^^^^^^^^^ missing `change` in implementation
   |
   = help: implement the missing item: `fn change(&mut self, _: <Self as yew::html::Component>::Properties) -> bool { todo!() }`

Implementing the missing method fixes the issue and the crate then compiles and yarn run start:dev starts successfully.

PR incoming.