Add PixelArtHive Sprite Upscaler (#513)

Co-authored-by: Mdtcy <24263933+Mdtcy@users.noreply.github.com>

README.md

@@ -188,6 +188,7 @@ _Great graphics placeholders and tools to turn that squared game into a picasso
 - :moneybag: [Pickle](http://www.pickleeditor.com/) - Another Pixel art Editor.
 - :tada: [PiskelApp](https://www.piskelapp.com/) - Free Online Pixel Art and Animated Sprite Tool.
 - :money_with_wings: [Pixanima](https://pixanima.app) - Free in-browser pixel-art and animation editor with layers, a frame timeline, GIF/sprite-sheet export, and an optional AI assistant.
+- :free: [PixelArtHive Sprite Upscaler](https://pixelarthive.com/pixel-art-upscaler) - Resize sprites for 2D games at whole-number scales without blur. Runs in the browser without uploading the sprite.
 - :moneybag: [Pixelator](http://pixelatorapp.com) - Turn any image into fancy pixel-art
 - :moneybag: [Pixelmator](https://www.pixelmator.com) - Full-featured image editing app for the Mac
 - :moneybag: [Pixen](https://github.com/Pixen/Pixen) - Pixel Art Editor for OSX