Fix import migration (#1227)

db/migrate/20240925112218_add_import_types.rb

@@ -1,7 +1,7 @@
 class AddImportTypes < ActiveRecord::Migration[7.2]
   def change
     change_table :imports do |t|
-      t.string :type, null: false
+      t.string :type
       t.string :date_col_label, default: "date"
       t.string :amount_col_label, default: "amount"
       t.string :name_col_label, default: "name"
@@ -19,6 +19,10 @@ class AddImportTypes < ActiveRecord::Migration[7.2]
       t.string :error
     end
 
+    Import.update_all(type: "TransactionImport")
+
+    change_column_null :imports, :type, false
+
     # Add import references so we can associate imported resources after the import
     add_reference :account_entries, :import, foreign_key: true, type: :uuid
     add_reference :accounts, :import, foreign_key: true, type: :uuid