The `dialog_id` field was inconsistently defined:
- In the `migrate_db()` function, it was set to `null=True`.
- In the model class, it was defined as `null=False`.
This inconsistency caused an issue during the initial deployment where
the database table did not allow `dialog_id` to be null. As a result,
calling `APITokenService.save(**obj)` in `system_app.py` raised the
following error:
```
peewee.IntegrityError: null value in column "dialog_id" violates not-null constraint
```
### What problem does this PR solve?
Error: peewee.IntegrityError: null value in column "dialog_id" violates
not-null constraint
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)
0e3e129a83