Test example prebuilt consumption with swiftbuild

Author: kateinoigakukun

.github/workflows/test.yml

@@ -207,7 +207,7 @@ jobs:
           find Examples/ActorOnWebWorker/.build/prebuilts -maxdepth 5 -print 2>/dev/null | sort || true
           find Examples/ActorOnWebWorker/.build -name workspace-state.json -print -exec sed -n '1,240p' {} \; || true
           cd Examples/ActorOnWebWorker
-          swift package --verbose ${SWIFT_PACKAGE_FLAGS} \
+          swift package --verbose ${SWIFT_PACKAGE_FLAGS} --build-system swiftbuild \
             --swift-sdk "${SWIFT_SDK_ID_wasm32_unknown_wasip1_threads:-${SWIFT_SDK_ID:-wasm32-unknown-wasip1-threads}}" \
             plugin --allow-writing-to-package-directory \
             js --use-cdn --output ./Bundle -c release