build: switch to AMO on firefox, remove update_url, bump to v4.7.1.1

Signed-off-by: Shengqi Chen <harry-chen@outlook.com>

Author: Harry-Chen

package.json

@@ -1,6 +1,6 @@
 {
   "name": "learn-helper",
-  "version": "4.7.1",
+  "version": "4.7.1.1",
   "author": "Harry Chen",
   "license": "MIT",
   "private": true,

wxt.config.ts

@@ -98,7 +98,6 @@ export default defineConfig({
     ...(browser === 'firefox' && {
       browser_specific_settings: {
         gecko: {
-          update_url: 'https://harrychen.xyz/learn/updates.json',
           id: '{b3a44052-5d0d-4ef9-9744-93b6f5ca7398}',
         },
       },