By Toby Sterling AMSTERDAM (Reuters) -The Dutch antitrust regulator on Monday issued a sixth weekly fine of 5 million euro ($5.7 million) against Apple for failure to comply with an order to open its App Store to alternative forms of payment for dating apps in the Netherlands. Earlier on Monday, Reuters reported that Apple has sent a letter to the Authority for Consumers and Markets (ACM) arguing it has already complied with the watchdog’s order. However, the ACM said in a statement it was not aware of any change in Apple’s position and it imposed the new fine. Apple’s practice of requiring de…