Image build is optimized.

.gitlab-ci.yml

@@ -22,9 +22,9 @@ variables:
 
 build:
   stage: build
-  image: docker:dind:20.10.21
+  image: docker:dind
   services:
-    - name: docker:dind:20.10.21
+    - name: docker:dind
       command: ["--tls=false", "--storage-driver=overlay2", "--mtu=1500", "--data-root=/mnt/volume"]
   before_script:
     - mkdir -p /mnt/volume