fix build (#602)

Author: flmel

.github/workflows/build.yml

@@ -7,8 +7,8 @@ jobs:
       - uses: actions/checkout@v2
       - uses: actions/setup-node@v2
         with:
-          node-version: '20'
+          node-version: "18"
       - name: Build Docusaurus docs
         run: |
-          cd website && npm install
-          npm run build
+          cd website && yarn
+          yarn run build