Removed background script declaration from the Chrome/Firefox extension

chrome-extension/manifest.json

@@ -3,9 +3,6 @@
     "name": "YoutubeDL-Material",
     "version": "0.4",
     "description": "The Official Firefox & Chrome Extension of YoutubeDL-Material, an open-source and self-hosted YouTube downloader.",
-    "background": {
-        "scripts": ["background.js"]
-    },
     "browser_action": {
         "default_icon": "favicon.png",
         "default_popup": "popup.html",