ci: use specific pnpm version

.github/workflows/ci.yml

@@ -20,7 +20,7 @@ jobs:
       - name: "Install Pnpm"
         uses: "pnpm/action-setup@v2"
         with:
-          version: "latest"
+          version: "8"
 
       - name: "Install Node.js"
         uses: "actions/setup-node@v3"