feat:autoupdate default useragent

app/src/main/java/io/legado/app/help/config/AppConfig.kt

@@ -2,6 +2,7 @@ package io.legado.app.help.config
 
 import android.content.Context
 import android.content.SharedPreferences
+import io.legado.app.BuildConfig
 import io.legado.app.constant.AppConst
 import io.legado.app.constant.PreferKey
 import io.legado.app.utils.*
@@ -293,7 +294,7 @@ object AppConfig : SharedPreferences.OnSharedPreferenceChangeListener {
     private fun getPrefUserAgent(): String {
         val ua = appCtx.getPrefString(PreferKey.userAgent)
         if (ua.isNullOrBlank()) {
-            return "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124 Safari/537.36"
+            return "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/" + BuildConfig.Cronet_Version + " Safari/537.36"
         }
         return ua
     }