resolve flake8 issues

.gitlab-ci.yml

-image: python:3.9
+image: python:3.11
 
 #services:
 #  - postgres:13

src/homework/serializers.py

 from rest_framework import serializers
 from django.utils import timezone
 from . import models
+from account.models import Profile
 from common.email import homework_corrected, new_homework
 
 

src/images/models.py

@@ -12,6 +12,7 @@ class Image(models.Model):
     def __str__(self):
         return str(self.id)
 
+
 # Deletes file from filesystem when File object is deleted.
 @receiver(models.signals.post_delete, sender=Image)
 def auto_delete_image_on_delete(sender, instance, **kwargs):

src/mentors/models.py

@@ -14,6 +14,7 @@ class Mentor(models.Model):
     def __str__(self):
         return self.name
 
+
 # Deletes file from filesystem when File object is deleted.
 @receiver(models.signals.post_delete, sender=Mentor)
 def auto_delete_image_on_delete(sender, instance, **kwargs):