fix image job update

.gitlab-ci.yml

@@ -1,5 +1,3 @@
-image: docker:19.03.12
-
 stages:
   - update
   - build
@@ -15,8 +13,7 @@ update:
   stage: update
   cache:
     key: blender-source
-  image:
-    - ubuntu:22.04
+  image: ubuntu:22.04
   script:
     - apt-get install -y git svn
     - mkdir -p /opt/blender-git/lib
@@ -28,6 +25,7 @@ update:
     - svn checkout https://svn.blender.org/svnroot/bf-blender/trunk/lib/linux_centos7_x86_64
 
 build:
+  image: docker:19.03.12
   rules:
     - changes:
         - build.json