fix: remove hardcoded pnpm version from frontend deploy workflow

pnpm/action-setup@v4 now reads from package.json packageManager field.

Author: rz1989s

.github/workflows/deploy-frontend.yml

@@ -13,8 +13,6 @@ jobs:
       - uses: actions/checkout@v4
 
       - uses: pnpm/action-setup@v4
-        with:
-          version: 9
 
       - uses: actions/setup-node@v4
         with: