fix: refactor index_together to indexes for Django 5.2 support (#36702)

lms/djangoapps/grades/migrations/0021_rename_persistentcoursegrade_passed_timestamp_course_id_passed_timestamp_course_id_idx_and_more.py

@@ -0,0 +1,23 @@
+# Generated by Django 4.2.20 on 2025-05-12 13:39
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('grades', '0020_alter_historicalpersistentsubsectiongradeoverride_options'),
+    ]
+
+    operations = [
+        migrations.RenameIndex(
+            model_name='persistentcoursegrade',
+            new_name='passed_timestamp_course_id_idx',
+            old_fields=('passed_timestamp', 'course_id'),
+        ),
+        migrations.RenameIndex(
+            model_name='persistentcoursegrade',
+            new_name='modified_course_id_idx',
+            old_fields=('modified', 'course_id'),
+        ),
+    ]

lms/djangoapps/grades/models.py

@@ -569,9 +569,9 @@ class PersistentCourseGrade(TimeStampedModel):
         unique_together = [
             ('course_id', 'user_id'),
         ]
-        index_together = [
-            ('passed_timestamp', 'course_id'),
-            ('modified', 'course_id')
+        indexes = [
+            models.Index(fields=['passed_timestamp', 'course_id'], name="passed_timestamp_course_id_idx"),
+            models.Index(fields=['modified', 'course_id'], name="modified_course_id_idx")
         ]
 
     # primary key will need to be large for this table