Gold: update max_length to accept Stripe price id (#11452)

Solves https://read-the-docs.sentry.io/issues/5542852208/

readthedocs/gold/migrations/0007_gold_level_varchar.py

@@ -0,0 +1,31 @@
+# Generated by Django 4.2.13 on 2024-07-08 09:06
+
+from django.db import migrations, models
+from django_safemigrate import Safe
+
+
+class Migration(migrations.Migration):
+    safe = Safe.before_deploy
+    dependencies = [
+        ("gold", "0006_remove_old_payments_field"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="golduser",
+            name="level",
+            field=models.CharField(
+                choices=[
+                    ("v1-org-5", "$5/mo"),
+                    ("v1-org-10", "$10/mo"),
+                    ("v1-org-15", "$15/mo"),
+                    ("v1-org-20", "$20/mo"),
+                    ("v1-org-50", "$50/mo"),
+                    ("v1-org-100", "$100/mo"),
+                ],
+                default="v1-org-5",
+                max_length=64,
+                verbose_name="Level",
+            ),
+        ),
+    ]

readthedocs/gold/models.py

@@ -37,7 +37,7 @@ class GoldUser(models.Model):
     )
     level = models.CharField(
         _("Level"),
-        max_length=20,
+        max_length=64,
         choices=LEVEL_CHOICES,
         default=LEVEL_CHOICES[0][0],
     )