Travis build fails in deploy step

[michielbdejong]

In https://travis-ci.org/solid/solid-panes/jobs/645705613 it was still passing:

[michielbdejong]

But in https://travis-ci.org/solid/solid-panes/builds/647278318 the build errored without a very clear explanation:

[michielbdejong]

Note that Travis distinguishes between 'Build errored (!)' and 'Build failed (x)':

[timea-solid]

We use GitHub CI now