Update blank.yml

Author: rain0r

.github/workflows/blank.yml

@@ -13,6 +13,8 @@ jobs:
   deploy:
     runs-on: ubuntu-latest
     steps:
+      - name: Checkout 
+        uses: actions/checkout@v2
       - name: Generate Swagger UI
         uses: Legion2/swagger-ui-action@v1
         with: