fix(ci): 添加playwright安装步骤

.github/workflows/build.yml

@@ -27,6 +27,8 @@ jobs:
         cache: 'pnpm'
     - name: Install dependencies
       run: pnpm install --frozen-lockfile
+    - name: Install playwright
+      run: pnpm exec playwright install
     - name: Build the slide
       run: pnpm run build
     - name: Export the slide into PDF