test notebook issues a warning when episode_functions are imported

[abostroem]

What is the problem?

When cell 8 is run:

from episode_functions import *

an error is issued regarding the latex formatting in lines 127 and 128 of episode_functions.py. An r should be added before the open quotes on both lines

plt.xlabel(r'$\phi_1$ [deg]')
plt.ylabel(r'$\phi_2$ [deg]')

and a new zip file built

Location of problem (optional)

https://github.com/datacarpentry/astronomy-python/blob/main/student_download/episode_functions.py#L127