[CI] Use --break-system-packages on Alpine (WebAssembly#6167)

Something changed in how CI sets up Python and now this is needed to avoid an error.

.github/workflows/ci.yml

@@ -195,7 +195,7 @@ jobs:
         ./alpine.sh apk add build-base cmake git python3 py3-pip clang ninja
 
     - name: install python dev dependencies
-      run: ./alpine.sh pip3 install -r requirements-dev.txt
+      run: ./alpine.sh pip3 install --break-system-packages -r requirements-dev.txt
 
     - name: cmake
       run: |