🌐(backend) internationalize demo

This allows the demo to generate user and filenames with other locales
than English, for all languages defined in the project's settings.
In particular, it allows the generation of accented names, which were
previously missing.

src/backend/demo/management/commands/create_demo.py

@@ -17,7 +17,8 @@ from core import models
 
 from demo import defaults
 
-fake = Faker()
+languages = [x for (x, y) in settings.LANGUAGES]
+fake = Faker(languages)
 
 logger = logging.getLogger("impress.commands.demo.create_demo")
 
@@ -127,7 +128,7 @@ def create_demo(stdout):
                     is_staff=False,
                     short_name=first_name,
                     full_name=f"{first_name:s} {random.choice(last_names):s}",
-                    language=random.choice(settings.LANGUAGES)[0],
+                    language=random.choice(languages),
                 )
             )
         queue.flush()
@@ -179,8 +180,7 @@ def create_demo(stdout):
                     is_superuser=False,
                     is_active=True,
                     is_staff=False,
-                    language=dev_user["language"]
-                    or random.choice(settings.LANGUAGES)[0],
+                    language=dev_user["language"] or random.choice(languages),
                 )
             )