migrations: Change migration 0639's dependency for backporting to 9.x.

This moves it "earlier" in the migrations graph, onto the last
migration in 9.x, and adds a merge migration to fold it back into
main's current migrations tip.

zerver/migrations/0639_zh_hant_tw_rename.py

@@ -18,7 +18,8 @@ def update_zh_hant_tw_language(apps: StateApps, schema_editor: BaseDatabaseSchem
 
 class Migration(migrations.Migration):
     dependencies = [
-        ("zerver", "0638_alter_stream_can_administer_channel_group"),
+        # The most recent 9.x migration, since this will be backported
+        ("zerver", "0622_backfill_imageattachment_again"),
     ]
 
     operations = [

zerver/migrations/0640_merge_20241211_1953.py

@@ -0,0 +1,12 @@
+# Generated by Django 5.0.9 on 2024-12-11 19:53
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("zerver", "0638_alter_stream_can_administer_channel_group"),
+        ("zerver", "0639_zh_hant_tw_rename"),
+    ]
+
+    operations = []