Use docker image from Docker hub.

.gitlab-ci.yml

-image: ahf/erlang:18.3
-
 before_script:
     - apt-get update -qq && apt-get install -y -qq libsodium-dev
     - erl +V
@@ -7,7 +5,14 @@ before_script:
 stages:
     - build
 
-job:
+test-18.3:
+    image: ahfaeroey/otp:18.3
     stage: build
     script:
-        - make compile
+        - make
+
+#test-19.0:
+#    image: ahfaeroey/otp:19.0
+#    stage: test
+#    script:
+#        - make check