refactor: Add pnpm installation step to Vercel deployment workflows

.gitea/workflows/vercel-preview.yaml

@@ -13,6 +13,8 @@ jobs:
       - uses: actions/checkout@v2
       - name: Install Vercel CLI
         run: npm install --global vercel@latest
+      - name: Install pnpm
+        run: npm install -g pnpm
       - name: Pull Vercel Environment Information
         run: vercel pull --yes --environment=preview --token=${{ secrets.VERCEL_TOKEN }}
       - name: Build Project Artifacts

.gitea/workflows/vercel-production.yaml

@@ -11,6 +11,8 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
+      - name: Install pnpm
+        run: npm install -g pnpm
       - name: Install Vercel CLI
         run: npm install --global vercel@latest
       - name: Pull Vercel Environment Information