Rename JSONModel to SerialisedModel 1/2

This class doesn’t actually wrap JSON, it wraps serialised data.

So this name feels better.

This commit only renames the file for an easier diff.

tests/app/notifications/test_process_notification.py

@@ -20,7 +20,7 @@ from app.notifications.process_notifications import (
     send_notification_to_queue,
     simulated_recipient
 )
-from app.json_models import TemplateJSONModel
+from app.serialised_models import TemplateJSONModel
 from notifications_utils.recipients import validate_and_format_phone_number, validate_and_format_email_address
 from app.v2.errors import BadRequestError
 from tests.app.db import create_service, create_template, create_api_key

tests/app/notifications/test_validators.py

@@ -23,7 +23,7 @@ from app.notifications.validators import (
     validate_and_format_recipient,
     validate_template,
 )
-from app.json_models import TemplateJSONModel
+from app.serialised_models import TemplateJSONModel
 from app.utils import get_template_instance
 
 from app.v2.errors import (