我有一个Flutter项目Android & IOS。今天，我启动了我的笔记本电脑，在很长一段时间后，尝试升级我的项目依赖，并添加Null安全。

pubspec.yaml

sdk: ">=2.19.0 < 3.0.0"

我使用的是MAC OS，我的项目位于我在/Volumes/Data/Projects/myproject中创建的分区中。当我尝试运行dart migrate命令时，收到以下消息。

Could not find a command named "migrate".

Usage: dart <command|dart-file> [arguments]

Global options:
-v, --verbose               Show additional command output.
    --version               Print the Dart SDK version.
    --enable-analytics      Enable analytics.
    --disable-analytics     Disable analytics.
    --suppress-analytics    Disallow analytics for this `dart *` run without changing the analytics configuration.
    -h, --help                  Print this usage information.

 Available commands:  
 analyze              Analyze Dart code in a directory.
 compilation-server   Control the resident frontend compiler.
 compile              Compile Dart to various formats.
 create               Create a new Dart project.
 devtools             Open DevTools (optionally connecting to an existing application).
 doc                  Generate API documentation for Dart projects.
 fix                  Apply automated fixes to Dart source code.
 format               Idiomatically format Dart source code.
 info                 Show diagnostic information about the installed tooling.
 language-server      Start Dart's analysis server.
 pub                  Work with packages.
 run                  Run a Dart program.
 test                 Run tests for a project.

我注意到可用命令列表中没有migrate命令。我可以从该文件夹运行其他命令，如dart fix、dart analyze等。
现在我必须手动迁移所有文件。如果我能运行一个迁移工具，那对我来说会更容易和更快。
谢谢你的时间！