chore: remove firefox extension manifest invalid field

Author: webfansplz

packages/firefox-extension/manifest.json

@@ -48,7 +48,6 @@
     "<all_urls>"
   ],
   "version": "7.7.6",
-  "version_name": "7.7.6",
   "web_accessible_resources": [
     "dist/user-app.js",
     "client/devtools-panel.css",