Fix compiler warning (#3138)
Fix compiler warning (#3138)

> using 'class' keyword for protocol inheritance is deprecated; use 'AnyObject' instead
abertelrud/swift-package-manager,apple/swift-package-manager,abertelrud/swift-package-manager,apple/swift-package-manager,apple/swift-package-manager,apple/swift-package-manager,abertelrud/swift-package-manager,abertelrud/swift-package-manager,abertelrud/swift-package-manager,apple/swift-package-manager