chore: 更新版本到 2.1.0 [skip ci]

manifest-firefox.json

@@ -105,8 +105,8 @@
     "https://arxiv.org/*",
     "https://f-droid.org/*"
   ],
-  "version": "2.0.5",
+  "version": "2.1.0",
   "web_accessible_resources": [
     "icons/*"
   ]
-}
+}