[openstreetmap/openstreetmap-website] travis: change dist to bionic (#2473)

[mmd]

Ok, test cases fail with a pretty extensive list of failures, which is quite good, because I can't get those tests to pass on my local bionic machine either. 

```
Error:
UserDiariesTest#test_showing_create_diary_entry:
ActionView::Template::Error: 
    app/views/layouts/_header.html.erb:105
    app/views/layouts/site.html.erb:5
    app/controllers/diary_entries_controller.rb:21:in `new'
    config/initializers/compressed_requests.rb:27:in `call'
    config/initializers/cors.rb:9:in `call'
    test/integration/user_diaries_test.rb:29:in `test_showing_create_diary_entry'
```

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/openstreetmap/openstreetmap-website/pull/2473#issuecomment-568253936
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/rails-dev/attachments/20191222/8f3298c9/attachment.html>