Add mods for subspace_storage in GitHub Actions (#455)

The GitHub Actions workflow was missing the mods needed to do the tests
for subspace_storage, causing coverage to be lower than it should be.

.github/workflows/node.js.yml

@@ -24,6 +24,8 @@ jobs:
     - run: npm i --no-optional
     - run: wget -q -O factorio.tar.gz https://www.factorio.com/get-download/latest/headless/linux64 && tar -xf factorio.tar.gz && rm factorio.tar.gz
     - run: npx lerna bootstrap --hoist
+    - run: node packages/lib/build_mod --source-dir packages/slave/lua/clusterio_lib --output-dir temp/test/sharedMods
+    - run: wget -q -O temp/test/sharedMods/subspace_storage_1.99.8.zip -L https://github.com/clusterio/subspace_storage/releases/download/1.99.6/subspace_storage_1.99.8.zip
     - run: npx lerna run build
     - name: Run tests
       if: ${{ matrix.node-version != '12.x' }}