ci: remove npm cache (no lockfile), use npm install

Author: OpenClaw

.github/workflows/ci.yml

@@ -15,7 +15,6 @@ jobs:
       - uses: actions/setup-node@v4
         with:
           node-version: ${{ matrix.node-version }}
-          cache: 'npm'
       - run: npm install
       - run: npm run build
       - run: npm test