[ci|tutorials] fix notebook plugin missing

.ci/gitlab/test_tutorials.bash

@@ -8,7 +8,8 @@ for fn in ${PYMOR_ROOT}/docs/source/tutorial*md ; do
   mystnb-to-jupyter -o "${fn}" "${fn/tutorial/..\/converted_tutorial}".ipynb
 done
 
+# manually add plugins to load that are excluded for other runs
 xvfb-run -a py.test ${COMMON_PYTEST_OPTS} -s --cov= -p no:pycharm \
-  docs/test_tutorials.py
+  -p nb_regression -p notebook docs/test_tutorials.py
 coverage xml