🗃️(backend) fix storage_location for existing deposited files

The `storage location` field was introduced in a previous release and filled
with a default value "AWS_S3". However, the correct enum value is "AWS".

Author: wilbrdt

src/backend/marsha/deposit/migrations/0008_depositedfile_fix_storage_location.py

@@ -0,0 +1,23 @@
+# Generated by Django 5.0.9 on 2025-07-14 13:31
+
+from django.db import migrations
+
+from marsha.core.defaults import AWS_S3
+
+
+def fix_storage_location_to_aws(apps, schema_editor):
+    """Fix the storage_location field for existing deposited files on AWS."""
+    DepositedFile = apps.get_model("deposit", "DepositedFile")
+    DepositedFile.objects.filter(storage_location="AWS_S3").update(
+        storage_location=AWS_S3
+    )
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("deposit", "0007_depositedfile_fill_storage_location"),
+    ]
+
+    operations = [
+        migrations.RunPython(fix_storage_location_to_aws, migrations.RunPython.noop),
+    ]