Todd Spangler NY Digital EditorDiscovery investors will be asked to approve the $43 billion deal to combine with WarnerMedia, which AT&T is spinning off, at a March 11 virtual meeting.Discovery announced the date in a letter to shareholders, which it disclosed in an SEC filing Thursday. On that same day, AT&T has scheduled a virtual investor conference where the company said it will provide “additional insight and expectations for financial and operational performance of AT&T’s Communications segment” following the close of the WarnerMedia transaction.The pact cleared a major hurdle this week after U.S.