Fix SwiftLint warning

Sources/ToolCore/ExtensionVisibility.swift

@@ -20,10 +20,13 @@ package enum ExtensionVisibility: String, CustomStringConvertible, ExpressibleBy
         switch self {
         case .public:
             "public"
+
         case .private:
             "private"
+
         case .internal:
             "internal"
+
         case .package:
             "package"
         }