build fail

**Describe the bug**
build fail

flutter version: 3.10.1

```
You may need to restart any open editors for them to read new settings.
Resolving dependencies... 
The lower bound of "sdk: '>=2.7.0 <3.0.0'" must be 2.12.0'
or higher to enable null safety.

The current Dart SDK (3.0.1) only supports null safety.

For details, see https://dart.dev/null-safety
```
