build packages before sync

.github/workflows/sync.yml

@@ -15,7 +15,21 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
-      # potentially a build step here
+      - name: Cache pnpm modules
+        uses: actions/cache@v3
+        with:
+          path: ~/.pnpm-store
+          key: ${{ runner.os }}-${{ hashFiles('**/pnpm-lock.yaml') }}
+          restore-keys: |
+            ${{ runner.os }}-
+      - uses: actions/setup-node@v3
+        with:
+          node-version: 18
+      - uses: pnpm/action-setup@v2.2.4
+        with:
+          run_install: true
+      - name: Build packages
+        run: pnpm build
       - name: Sync
         run: .github/sync-to-mirrors.sh
         env: