Make sure the default backend is Dawn in Next branches

Author: eliemichel

data/WebGPU-distribution-v0.3.0-gamma-default-to-dawn.zip

@@ -4,7 +4,7 @@ Hello WebGPU <span class="bullet">🟢</span>
 ```{lit-setup}
 :tangle-root: 001 - Hello WebGPU - Next
 :parent: 000 - Project setup - Next
-:fetch-files: ../../data/WebGPU-distribution-v0.3.0-gamma.zip
+:fetch-files: ../../data/WebGPU-distribution-v0.3.0-gamma-default-to-dawn.zip
 ```
 
 *Resulting code:* [`step001-next`](https://github.com/eliemichel/LearnWebGPU-Code/tree/step001-next)