Swift: Update to package manager 5.1

swift/Sources/GildedRose/Item.swift

@@ -0,0 +1,18 @@
+
+public class Item {
+    public var name: String
+    public var sellIn: Int
+    public var quality: Int
+    
+    public init(name: String, sellIn: Int, quality: Int) {
+        self.name = name
+        self.sellIn = sellIn
+        self.quality = quality
+    }
+}
+
+extension Item: CustomStringConvertible {
+    public var description: String {
+        return self.name + ", " + String(self.sellIn) + ", " + String(self.quality);
+    }
+}