Update docker-ubuntu-image.yml

Author: akme

.github/workflows/docker-ubuntu-image.yml

@@ -13,6 +13,9 @@ jobs:
   build-and-push:
     runs-on: ubuntu-latest
     steps:
+      -
+        name: Checkout
+        uses: actions/checkout@v2
 
       -
         name: Set up QEMU