Apt-get update fails on builds with Ubuntu images

Ah we forgot about Travis :see_no_evil: Bintray has shut down, see: Announcing new apt and rpm repositories - The Crystal Programming Language

Further reading also at: Bintray will be gone at the end of April · Issue #10626 · crystal-lang/crystal · GitHub

Also consider this: The Travis CI Blog: ORG Shutdown

I’ll look into updating the Travis integration to use the new repositories.

Johannes actually thought of it, it’s just that nobody from Travis reacted to it in time: Update repository for crystal to OBS by straight-shoota · Pull Request #1987 · travis-ci/travis-build · GitHub