Update konva.d.ts for getRGB

getRGB returns an object with RGB values, not a string. I've set up a type RGB. 

Feel free to edit to your heart's content.

konva.d.ts

@@ -86,9 +86,15 @@ declare namespace Konva {
     | 'color'
     | 'luminosity';
                    
+  export interface RGB {
+    r: number;
+    g: number;
+    b: number;
+  }
+
   export class Util {
     static getRandomColor(): string;
-    static getRGB(color: string): string;
+    static getRGB(color: string): RGB;
   }
 
   type EasingFn = (