Tests should not depend on Matrix-nio, that uses lxml that needs a lot of dependencies and a lot of time to build

apps/participation/tests.py

@@ -1,4 +1,3 @@
-import os
 from datetime import timedelta
 
 from django.contrib.auth.models import User
@@ -705,7 +704,6 @@ class TestStudentParticipation(TestCase):
 
         call_command('fix_matrix_channels')
         call_command('setup_third_phase')
-        os.remove(".matrix_avatar")
 
 
 class TestAdmin(TestCase):