add submitter timezone

db/migrate/20250613160132_add_timezone_to_submitters.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class AddTimezoneToSubmitters < ActiveRecord::Migration[8.0]
+  def change
+    add_column :submitters, :timezone, :string
+  end
+end