Ref: apps/users/management/commands/make_superuser.py

1. Test make_superuser — success: Call the command with a valid email; assert is_staff=True and is_superuser=True on the user.
2. . Test make_superuser — user not found: Call with an unknown email; assert CommandError is raised.

Some considerations:

• Make use of factories if they exist. Otherwise pls create some.
• Test coverage should increase (currently 0% for this file)