chore(ci): remove pinned pnpm version from GH Action steps

Remove the explicit `with: version: 9` lines from multiple GitHub Actions workflows
(auto-i18n.yml, nightly-build.yml, pr-ci.yml, update-app-upgrade-config.yml,
sync-to-gitcode.yml, release.yml). The workflows still call `pnpm/action-setup@v4`
but no longer hardcode a pnpm version.

This simplifies maintenance and allows the action to resolve an appropriate pnpm
version (or use its default) without needing updates whenever the pinned
version becomes outdated. It reduces churn when bumping pnpm across CI configs
and prevents accidental pin drift between workflow files.

.github/workflows/auto-i18n.yml

@@ -34,8 +34,6 @@ jobs:
 
       - name: 📦 Install pnpm
         uses: pnpm/action-setup@v4
-        with:
-          version: 9
 
       - name: 📂 Get pnpm store directory
         id: pnpm-cache

.github/workflows/nightly-build.yml

@@ -67,8 +67,6 @@ jobs:
 
       - name: Install pnpm
         uses: pnpm/action-setup@v4
-        with:
-          version: 9
 
       - name: Get pnpm store directory
         id: pnpm-cache

.github/workflows/pr-ci.yml

@@ -30,8 +30,6 @@ jobs:
 
       - name: Install pnpm
         uses: pnpm/action-setup@v4
-        with:
-          version: 9
 
       - name: Get pnpm store directory
         id: pnpm-cache

.github/workflows/release.yml

@@ -58,8 +58,6 @@ jobs:
 
       - name: Install pnpm
         uses: pnpm/action-setup@v4
-        with:
-          version: 9
 
       - name: Get pnpm store directory
         id: pnpm-cache

.github/workflows/sync-to-gitcode.yml

@@ -50,8 +50,6 @@ jobs:
 
       - name: Install pnpm
         uses: pnpm/action-setup@v4
-        with:
-          version: 9
 
       - name: Clean node_modules
         if: ${{ github.event.inputs.clean == 'true' }}

.github/workflows/update-app-upgrade-config.yml

@@ -157,8 +157,6 @@ jobs:
       - name: Install pnpm
         if: steps.check.outputs.should_run == 'true'
         uses: pnpm/action-setup@v4
-        with:
-          version: 9
 
       - name: Install dependencies
         if: steps.check.outputs.should_run == 'true'