chore: use pnpm/action-setup instead of corepack

Author: shuuji3

.github/workflows/ci.yml

@@ -20,7 +20,7 @@ jobs:
       pull-requests: write
     steps:
       - uses: actions/checkout@v4
-      - run: corepack enable
+      - uses: pnpm/action-setup@v4
       - uses: actions/setup-node@v4
         with:
           node-version: 20