Update themes.json

Author: zachvlat

themes.json

@@ -2303,7 +2303,7 @@
     "title": "Dynamic Color",
     "link": "https://github.com/zachvlat/Dynamic-Color-Firefox-Theme",
     "description": "Dark, dynamic (based on the system's accent color), theme for Firefox ",
-    "image": "https://private-user-images.githubusercontent.com/28532979/576430087-7bb875ea-4b77-41b7-b1ae-9dfe097f5706.png?jwt=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.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.h40T5AlVsoVxaMQhiNtjeBT4BDJmhYbnFNHSGBprh4U",
+    "image": "https://raw.githubusercontent.com/zachvlat/Dynamic-Color-Firefox-Theme/refs/heads/main/thumbnail.png",
     "tags": [
       "zachvlat",
       "dark",