Fix Travis build

Author: tchiotludo

.travis.yml

@@ -26,7 +26,7 @@ script:
   - echo "$DOCKER_PASSWORD" | docker login -u "$DOCKER_USERNAME" --password-stdin
   # Gradle
   - ./gradlew --console=plain test
-  - ./gradlew --console=plain jar
+  - ./gradlew --console=plain shadowJar
   # Docker Build
   - cp build/libs/kafkahq-*.jar docker/app/kafkahq.jar
   - docker build . -t $TRAVIS_COMMIT