Image build is optimized.

.gitlab-ci.yml

@@ -45,9 +45,9 @@ after_script:
 
 build:
   stage: build
-  image: docker:latest
+  image: docker:20.10.16
   services:
-    - name: docker:dind
+    - name: docker:20.10.16-dind
       command: ["--host=tcp://0.0.0.0:2375", "--tls=false", "--storage-driver=overlay2", "--mtu=1500", "--data-root=/mnt/volume"]
   script:
     - docker info
@@ -59,9 +59,9 @@ build:
 
 deploy:
   stage: deploy
-  image: docker:latest
+  image: docker:20.10.16
   services:
-    - name: docker:dind
+    - name: docker:20.10.16-dind
       command: ["--tls=false", "--storage-driver=overlay2", "--mtu=1500", "--data-root=/mnt/volume"]
   script:
     - docker pull 22baar1mst/asyst-nlp-grader:latest