🚚(backend) rename Impress to Meet

I have updated all references of "Impress" to "Meet".
Migrations were manually updated and not regenerated. Never-mind,
they all will be squashed before the first release.

I have also searched for reference to "Magnify", and replaced them
by "Meet".

While updating the backend sources, I have also fixed other parts of
the project, namely:
- Compose file
- Github documentation and CI
- Makefile commands

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

@@ -18,7 +18,7 @@ from demo import defaults
 
 fake = Faker()
 
-logger = logging.getLogger("impress.commands.demo.create_demo")
+logger = logging.getLogger("meet.commands.demo.create_demo")
 
 
 def random_true_with_probability(probability):