fix: add blank=true to SlideSubmission.doc (#8688)

Allows admin to save an instance with a null doc reference, which was already permitted.

ietf/meeting/migrations/0011_alter_slidesubmission_doc.py

@@ -0,0 +1,26 @@
+# Generated by Django 4.2.19 on 2025-03-17 09:37
+
+from django.db import migrations
+import django.db.models.deletion
+import ietf.utils.models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("doc", "0025_storedobject_storedobject_unique_name_per_store"),
+        ("meeting", "0010_alter_floorplan_image_alter_meetinghost_logo"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="slidesubmission",
+            name="doc",
+            field=ietf.utils.models.ForeignKey(
+                blank=True,
+                null=True,
+                on_delete=django.db.models.deletion.SET_NULL,
+                to="doc.document",
+            ),
+        ),
+    ]

ietf/meeting/models.py

@@ -1385,7 +1385,7 @@ class SlideSubmission(models.Model):
     apply_to_all = models.BooleanField(default=False)
     submitter = ForeignKey(Person)
     status      = ForeignKey(SlideSubmissionStatusName, null=True, default='pending', on_delete=models.SET_NULL)
-    doc         = ForeignKey(Document, null=True, on_delete=models.SET_NULL)
+    doc         = ForeignKey(Document, blank=True, null=True, on_delete=models.SET_NULL)
 
     def staged_filepath(self):
         return os.path.join(settings.SLIDE_STAGING_PATH , self.filename)