ci: workaround corepack issue with actions

Author: alexzhang1030

.github/workflows/ci.yml

@@ -21,7 +21,9 @@ jobs:
           node-version: lts/*
 
       - name: Install pnpm
-        uses: corepack enable pnpm
+        # https://github.com/nitrojs/nitro/pull/3060
+        # https://github.com/nodejs/corepack/pull/614
+        uses: npm i -g --force corepack && corepack enable pnpm
 
       - name: Setup ni
         run: npm i -g @antfu/ni