fix(ci): remove duplicate pnpm version specification

pnpm/action-setup will read version from package.json packageManager field

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: 7Jerrybf

.github/workflows/ci.yml

@@ -20,8 +20,6 @@ jobs:
 
       - name: Install pnpm
         uses: pnpm/action-setup@v4
-        with:
-          version: 9
 
       - name: Setup Node.js ${{ matrix.node-version }}
         uses: actions/setup-node@v4
@@ -47,8 +45,6 @@ jobs:
 
       - name: Install pnpm
         uses: pnpm/action-setup@v4
-        with:
-          version: 9
 
       - name: Setup Node.js
         uses: actions/setup-node@v4