Update shadow plugin to version 5.0.0 to fix shadow jar build/upload
Update shadow plugin to version 5.0.0 to fix shadow jar build/upload

Older versions would name the resulting jar file incorrectly, which
caused our Travis build to silently not upload it.

bendisposto/prob2-ui,bendisposto/prob2-ui,bendisposto/prob2-ui,bendisposto/prob2-ui