AIR TRAVELAllegiant Air and Sun Country complete merger, creating larger budget airline for travelersAllegiant Air said Wednesday it has completed its purchase of Sun Country Airlines, finalizing a deal that combines two low-cost carriers at a turbulent time for the budget airline industry following the recent shutdown of rival Spirit Airlines. Las Vegas-based Allegiant said the transaction closed after receiving required regulatory and shareholder approvals. When the deal was first announced in January, Allegiant said it was valued at about $1.5 billion, including debt. “Today marks a defining moment in Allegiant’s history as we officially join forces with Sun Country,”…