tests failing on CI

[noerw]

Tests (even those which passed previously) are failing on travis since at least 26.04.2019.
On CRAN they fail as well.
Running them locally works.

The issue seems to be a timeout, as the builds abort with the message

* checking tests ...
  Running ‘testthat.R’
No output has been received in the last 10m0s, this potentially indicates a stalled build or something wrong with the build itself.
Check the details on how to adjust your build configuration on: https://docs.travis-ci.com/user/common-build-problems/#Build-times-out-because-no-output-was-received

Recently introduced ratelimits on the API might be the issue?