ci(native): add checkout step

Author: thewtex

.github/workflows/native.yml

@@ -15,6 +15,8 @@ jobs:
     runs-on: ubuntu-22.04
 
     steps:
+      - uses: actions/checkout@v4
+
       - uses: prefix-dev/setup-pixi@v0.8.1
 
       - name: Build and Test ITK-Wasm