Fix docker build

.gitlab-ci.yml

@@ -1,4 +1,5 @@
-image: ubuntu:bionic
+# Official docker image.
+image: docker:19.03.1
 
 variables:
   GIT_SUBMODULE_STRATEGY: recursive
@@ -39,9 +40,10 @@ build:
 package-deploy:
   stage: package
   services:
-    - docker:dind
+    - docker:19.03.1-dind
   variables:
     DOCKER_HOST: "tcp://docker:2375"
+    DOCKER_TLS_CERTDIR: ""
     LANG: C.UTF-8
   before_script:
     - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY
@@ -59,6 +61,7 @@ package:
     - docker:dind
   variables:
     DOCKER_HOST: "tcp://docker:2375"
+    DOCKER_TLS_CERTDIR: ""
     LANG: C.UTF-8
   before_script:
     - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY