nbinteract failed with matplotlib

[OrFixelAlgorithms]

Hi,
I used this requirements file:
https://github.com/FixelAlgorithmsTeam/FixelCourses/blob/master/requirements.txt

and this ipynb:
https://github.com/FixelAlgorithmsTeam/FixelCourses/blob/master/Test1.ipynb

when I convert to HTML and open the file I get the following error:

Any suggestions?