ci: specify pnpm version

Author: stone-zeng

Diff for: .github/workflows/build.yml

@@ -8,8 +8,10 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v3
         with:
-            node-version: 18
+          node-version: 18
       - uses: pnpm/action-setup@v2
+        with:
+          version: 8
       - name: Install dependencies
         run: pnpm install
       - name: Build