Rename repository address of Theme - Elementary

Renamed repository address of `Theme - Elementary`, because I've changed my username on GitHub.

repository/t.json

@@ -778,7 +778,7 @@
 		},
 		{
 			"name": "Theme - Elementary",
-			"details": "https://github.com/piqus/sublime-elementary",
+			"details": "https://github.com/piotrkubisa/sublime-elementary",
 			"labels": ["theme", "color scheme"],
 			"previous_names": ["Mustang Extended Color Scheme"],
 			"releases": [