ruff + submissions validation

opus_submitter/submissions/models.py

@@ -1,9 +1,7 @@
 from django.db import models
 from django.contrib.auth import get_user_model
-from django.utils import timezone
 from django.core.exceptions import ValidationError
 import uuid
-import os
 
 User = get_user_model()
 
@@ -242,11 +240,11 @@ class Submission(models.Model):
     validated_at = models.DateTimeField(
         null=True, blank=True, help_text="When this submission was validated"
     )
-    
+
     # Manual validation request
     manual_validation_requested = models.BooleanField(
-        default=False, 
-        help_text="Whether the user specifically requested manual validation"
+        default=False,
+        help_text="Whether the user specifically requested manual validation",
     )
 
     # Timestamps