fix failing CI

Author: fangohr

Dockerfile

@@ -12,8 +12,16 @@ RUN apt-get install -y build-essential cmake cython3 python3-dev python3-pip \
     liblapack-dev libopenblas-dev \
     wget
 
+# ----------
+# hack to fix sudden breakage in CI
+# (fix from https://github.com/getsentry/sentry/issues/3143)
+# (first occurance of fail at https://travis-ci.org/computationalmodelling/fidimag/builds/319708056?utm_source=github_status&utm_medium=notification)
+# (which is part of this pull request: https://github.com/computationalmodelling/fidimag/pull/106)
+RUN pip3 install --upgrade setuptools==20.4
+# ----------
+
 RUN pip3 install ipywidgets nbval pyvtk six
-    
+
 WORKDIR /fidimag
 ADD . /fidimag
 RUN ./bin/install-sundials.sh