[books] Clean up koreader imports and data storage

vrobbler/apps/books/migrations/0021_remove_book_koreader_authors_remove_book_koreader_id_and_more.py

@@ -0,0 +1,25 @@
+# Generated by Django 4.2.16 on 2024-10-17 20:08
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("books", "0020_author_comicvine_data_book_comicvine_data_and_more"),
+    ]
+
+    operations = [
+        migrations.RemoveField(
+            model_name="book",
+            name="koreader_authors",
+        ),
+        migrations.RemoveField(
+            model_name="book",
+            name="koreader_id",
+        ),
+        migrations.RemoveField(
+            model_name="book",
+            name="koreader_md5",
+        ),
+    ]