Update astro.yml

Author: ColinWttt

.github/workflows/astro.yml

@@ -32,6 +32,9 @@ jobs:
           cache: "pnpm"
           cache-dependency-path: ${{ env.BUILD_PATH }}/pnpm-lock.yaml
 
+      - name: Install pnpm
+        run: npm install -g pnpm
+
       - name: Setup Pages
         id: pages
         uses: actions/configure-pages@v5