Allow books with no authors

ram/bookshelf/migrations/0015_alter_book_authors.py

@@ -0,0 +1,18 @@
+# Generated by Django 5.1.2 on 2024-11-26 22:21
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("bookshelf", "0014_book_published"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="book",
+            name="authors",
+            field=models.ManyToManyField(blank=True, to="bookshelf.author"),
+        ),
+    ]