ci: fix gh-pages (#105)

Author: xrkffgg

.github/workflows/gh-pages.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - run: npm install
+      - run: yarn
       - run: npm run docs:build
       - name: Deploy
         uses: peaceiris/actions-gh-pages@v3