3.4.0迁移、flutter更新后、迁移报错修复OK

 buildscript {
 buildscript {
-    ext.kotlin_version = '1.3.50'
+    // ext.kotlin_version = '1.3.50'
+    ext.kotlin_version = '1.6.20'
     repositories {
     repositories {
         google()
         google()
         jcenter()
         jcenter()

@@ -869,7 +869,7 @@ packages:
       name: platform
       name: platform
       url: "https://pub.flutter-io.cn"
       url: "https://pub.flutter-io.cn"
     source: hosted
     source: hosted
-    version: "3.0.0"
+    version: "3.1.0"
   plugin_platform_interface:
   plugin_platform_interface:
     dependency: transitive
     dependency: transitive
     description:
     description: