Update .gitlab-ci.yml

.gitlab-ci.yml

 image: maven:3.5.0-jdk-8
 
+
+
 build:
-  script: "mvn install -B"
+  script: "mvn compile -B -T 2"
+
+
+test: 
+  dependencies:
+    - build
+  script: "mvn test -B"
+
+package: 
+  dependencies:
+    - test
+  script: "mvn package -DskiptTests=true -B"
+  
+
+doc: 
+  dependencies:
+    - test
+  script: "mvn site:site -DskiptTests=true -B"
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