feat(ci): cache npm packages

Author: dairiki

.github/workflows/deploy.yml

@@ -26,9 +26,13 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
+
       - uses: actions/setup-node@v4
         with:
           node-version: "lts/*"
+          cache: npm
+          cache-dependency-path: webpack/package-lock.json
+
       - uses: pdm-project/setup-pdm@v4
         with:
           cache: true