https://ipsw.me/download/iPad6,8/17A878/
Download iPadOS 13.1.3 (17A878) for iPad Pro 12.9-inch (Cellular) / IPSW Downloads
Download iPadOS 13.1.3 (17A878) for iPad Pro 12.9-inch (Cellular). IPSW Downloads provides download links and information for Apple's operating systems,...