By Zeba Siddiqui and Raphael Satter SAN FRANCISCO/WASHINGTON (Reuters) -The hack of the U.S. Securities and Exchange Commission’s official account on X on Tuesday renewed concerns about the social media platform’s security since its takeover by billionaire Elon Musk in 2022. The hackers posted false news about a widely anticipated announcement the SEC was expected to make about bitcoin, leading the cryptocurrency’s price to spike and alarming observers. The false post on @SECGov said the securities regulator had approved exchange-traded funds to hold bitcoin. The SEC deleted the post about 30 …