Redirects: remove null option from position field (#10991)

When creating a new redirect using the API,
omitting the position field would result in a default of None
instead of 0.

Ref https://read-the-docs.sentry.io/issues/4802345808/?project=148442&query=is%3Aunresolved&referrer=issue-stream&statsPeriod=24h&stream_index=0

Author: stsewd

readthedocs/redirects/migrations/0008_alter_redirect_position.py

@@ -0,0 +1,21 @@
+# Generated by Django 4.2.8 on 2024-01-03 20:13
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("redirects", "0007_migrate_to_new_syntax"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="redirect",
+            name="position",
+            field=models.PositiveIntegerField(
+                default=0,
+                help_text="Order of execution of the redirect.",
+                verbose_name="Position",
+            ),
+        ),
+    ]

readthedocs/redirects/models.py

@@ -113,7 +113,6 @@ class Redirect(models.Model):
     position = models.PositiveIntegerField(
         _("Position"),
         default=0,
-        null=True,
         help_text=_("Order of execution of the redirect."),
     )