can't create v12 rooms

### Steps to reproduce

1. Try to create a room at a server which default to v12
2. Get an error about `power_level_content_override.users` (creator user IDs are not allowed in the `users` field)

### Outcome

#### What did you expect?
to be able to create rooms
#### What happened instead?
```
MatrixError: [400] M_INVALID_PARAM: creator user IDs are not allowed in the `users` field
```

### Operating system

NixOS

### Browser information

Chromium

### URL for webapp

call.vladexa.xyz

### Will you send logs?

No