Delete old gitlab-ci.yml

gitlab-ci.yml

-image: openjdk:latest
-
-build:
-    stage: build
-    script:
-        - javac SiteGen.java
-
-test:
-    stage: test
-    script:
-        - javac -cp "./junit-platform-console-standalone-1.8.1.jar" SiteGenTest.java SiteGen.java
-        - java -jar junit-platform-console-standalone-1.8.1.jar -cp "." -c SiteGenTest 
-
-pages:
-    stage: deploy
-    script:
-        - javac SiteGen.java
-        - java SiteGen
-    artifacts:
-        paths:
-            - public
-    only:
-        - main