change install command

.gitlab-ci.yml

@@ -69,7 +69,7 @@ docker-deploy-main-test:
     ## Install ssh-agent if not already installed, it is required by Docker.
     ## (change apt-get to yum if you use an RPM-based image)
     ##
-    - 'command -v ssh-agent >/dev/null || ( apt-get update -y && apt-get install openssh-client rsync -y )'
+    - 'command -v ssh-agent >/dev/null || ( apk add openssh-client rsync -y )'
     ##
     ## Run ssh-agent (inside the build environment)
     ##