WASHINGTON (Reuters) – U.S. financial regulators on Thursday told banks to upgrade their systems as soon as possible if they are vulnerable to the recently uncovered Heartbleed bug, which exposes data to hackers. The Federal Financial Institutions Examination Council, an interagency group that includes the Federal Reserve and the Federal Deposit Insurance Corp, said banks also should set up temporary patches for any systems using the Web encryption program known as OpenSSL and warn their outside service providers to take action. …