UForce, a London-based drone startup, is in discussions to raise new financing at a valuation of about $5 billion, according to people familiar with the matter.The company is seeking about $500 million led by Valor Equity Partners, the venture firm run by SpaceX board member and Elon Musk ally Antonio Gracias, the people said, asking not to be identified because the information is private. The round is not closed and details could change, they said....