Update to Android SDK 28

Dockerfile

@@ -5,7 +5,7 @@
 # https://git.faked.org/jan/gitlab-ci-android
 #
 
-FROM ubuntu:17.10
+FROM ubuntu:18.04
 MAINTAINER Jan Grewe <jan@faked.org>
 
 ENV VERSION_SDK_TOOLS "4333796"

packages.txt

 add-ons;addon-google_apis-google-24
-build-tools;27.0.3
+build-tools;28.0.2
 extras;android;m2repository
 extras;google;m2repository
 extras;google;google_play_services
 extras;m2repository;com;android;support;constraint;constraint-layout;1.0.2
 extras;m2repository;com;android;support;constraint;constraint-layout-solver;1.0.2
 platform-tools
-platforms;android-27
+platforms;android-28