fix image extension

Author: Developerayo

package.json

@@ -18,7 +18,7 @@
     "keywords": [
         "Tsukuyomi, vscodetheme, vscode, naruto, anime, dark, developerayo, color-theme, Night Theme" ],
 
-    "icon": "tsukuyomi.jpg",
+    "icon": "tsukuyomi.png",
     "repository": {
         "type": "git",
         "url": "https://github.com/Developerayo/tsukuyomi-vscode-theme.git"