add cache for pnpm

Author: mansona

.github/workflows/ci.yml

@@ -46,6 +46,8 @@ jobs:
         uses: actions/setup-node@v4
         with:
           node-version: ${{ matrix.node-version }}
+          cache: pnpm
+      # for test cache hits
       - run: pnpm add -g [email protected]
       - run: pnpm install
       - run: pnpm run ${{ matrix.test-command }} -- --retries 1