[no bump] Shift plugin icon index down by one

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

plugin.json

@@ -4,7 +4,7 @@
   "description": "Adds a Forward action to media opened from telegra.ph pages and rich messages (single media and carousels): downloads the media and re-sends it from your account with a link back to its source.",
   "author": "@lyuksovannyy",
   "version": "1.1.2",
-  "icon": "exteraGramPluginIcons/4",
+  "icon": "exteraGramPluginIcons/3",
   "app_version": ">=12.5.1",
   "sdk_version": ">=1.4.4.3",
   "requirements": []