Fix tests.py, add migration, fix pylint

main/migrations/0018_alter_unassignedticket_ticket_id.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.2.3 on 2021-05-20 17:00
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('main', '0017_auto_20210408_1943'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='unassignedticket',
+            name='ticket_id',
+            field=models.IntegerField(help_text='Номер тикета, для которого сняли ответственного'),
+        ),
+    ]