Update src/main/java/fi/utu/tech/Main.java,...

Update src/main/java/fi/utu/tech/Main.java, src/main/resources/application.css, src/main/resources/soundeffects/.gitkeep, src/main/resources/soundeffects/explosion.wav, src/main/resources/soundeffects/healthpickup.wav, src/main/resources/soundeffects/invaderkilled.wav, src/main/resources/soundeffects/shoot.wav, src/main/resources/soundeffects/spaceInvadersRemix.wav, src/main/resources/images/barrier1.png, src/main/resources/images/barrier2.png, src/main/resources/images/barrier3.png, src/main/resources/images/barrier4.png, src/main/resources/images/barrier5.png, src/main/resources/images/barrier6.png, src/main/resources/images/bullet.png, src/main/resources/images/explosion.png, src/main/resources/images/gameover.png, src/main/resources/images/invader1.png, src/main/resources/images/invader2.png, src/main/resources/images/invader3.png, src/main/resources/images/life.png, src/main/resources/images/player.png, .gitlab-ci.yml, pom.xml files