checkout before run

.github/workflows/build-container.yml

@@ -1,5 +1,5 @@
 ---
-name: Create Container
+name: Build Container
 on:
   pull_request:
     branches:
@@ -8,13 +8,9 @@ on:
     branches:
       - main
 
-env:
-  IMAGE_NAME: isogenerator
-  IMAGE_REGISTRY: "ghcr.io/${{ github.repository_owner }}"
-
 jobs:
   push-image:
-    name: Build and push image
+    name: Build and push container image
     runs-on: ubuntu-22.04
     permissions:
       contents: read
@@ -30,6 +26,9 @@ jobs:
           - version: 39
             support: latest
     steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
       - name: Build image
         uses: JasonN3/build-action@action
         with: