use ubuntu, install maven

.gitlab-ci.yml

@@ -10,10 +10,13 @@ build:
     - mvn package
 
 test_parsing:
-  image: maven:latest
+  image: ubuntu:rolling
   stage: test
   tags:
     - docker
+  before_script:
+    - apt update
+    - apt install -y build-essential openjdk-13-jre-headless maven
   script:
      - make testJava