added yarn build to actions script

Author: VirtualParticle

.github/workflows/main.yml

@@ -13,6 +13,7 @@ jobs:
           node-version: '15.x'
           registry-url: 'https://registry.npmjs.org'
       - run: yarn
+      - run: yarn build
       - run: yarn publish
         env:
           NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}