Venture capital firm Kleiner Perkins is in talks to lead a funding round of $350 million for cybersecurity startup Chainguard Inc., according to people familiar with the matter, lifting its valuation to $3.5 billion.The deal would roughly triple the company’s value from a financing deal last year, underscoring the growing need for secure tools for software development. Representatives for Chainguard and Kleiner Perkins declined emailed requests for comment, and the people familiar with their dis...