Fix Python kernel to Python 3

2 jobs from test_minimal_example_failing in 13 minutes and 30 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
failed #124994753
test_non_release_branches

00:13:30

failed #124994606
test_non_release_branches

00:00:15

 
Name Stage Failure
failed
test_non_release_branches Test
$ cd ../scripts
$ xvfb-run -a python3 minimal_example_perovskite_100.py
/usr/lib/python3/dist-packages/h5py/__init__.py:34: FutureWarning: Conversion of the second argument of issubdtype from `float` to `np.floating` is deprecated. In future, it will be treated as `np.float64 == np.dtype(float).type`.
from ._conv import register_converters as _register_converters
WARNING:hyperspy_gui_traitsui:The TkAgg matplotlib backend is not supported by the installed traitsui version and the ETS toolkit has been set to null. To set the ETS toolkit independently from the matplotlib backend, set it before importing matplotlib. See http://hyperspy.readthedocs.io/en/stable/user_guide/getting_started.html for more information.
WARNING:hyperspy_gui_traitsui:The traitsui GUI elements are not available.
0%| | 0/25 [00:00<?, ?it/s] 4%|4 | 1/25 [00:02<00:48, 2.03s/it] 8%|8 | 2/25 [00:03<00:46, 2.00s/it] 12%|#2 | 3/25 [00:05<00:43, 1.97s/it] 16%|#6 | 4/25 [00:07<00:40, 1.93s/it] 20%|## | 5/25 [00:09<00:38, 1.91s/it] 24%|##4 | 6/25 [00:11<00:35, 1.88s/it] 28%|##8 | 7/25 [00:13<00:32, 1.82s/it] 32%|###2 | 8/25 [00:13<00:24, 1.44s/it] 36%|###6 | 9/25 [00:14<00:18, 1.14s/it] 40%|#### | 10/25 [00:14<00:13, 1.08it/s] 44%|####4 | 11/25 [00:14<00:10, 1.29it/s] 48%|####8 | 12/25 [00:15<00:08, 1.62it/s] 64%|######4 | 16/25 [00:15<00:03, 2.28it/s] 84%|########4 | 21/25 [00:15<00:01, 3.19it/s] 100%|##########| 25/25 [00:15<00:00, 1.62it/s]
0%| | 0/1079 [00:00<?, ?it/s] 28%|##8 | 305/1079 [00:00<00:00, 1645.66it/s] 89%|########9 | 965/1079 [00:00<00:00, 2123.83it/s] 100%|##########| 1079/1079 [00:00<00:00, 3577.82it/s]Segmentation fault (core dumped)
ERROR: Job failed: exit code 1