'BoxShadowListMixRef' can't be assigned to the parameter type 'List<BoxShadowMix>'

### Package version

_No response_

### Flutter version

```
final token = BoxShadowToken('effect');
BoxStyler().boxShadows(token.mix());
```

Then we found that an error.
```
The argument type 'BoxShadowListMixRef' can't be assigned to the parameter type 'List'. dart[argument_type_not_assignable](https://dart.dev/diagnostics/argument_type_not_assignable)
```

### Steps to reproduce

```
final token = BoxShadowToken('effect');
BoxStyler().boxShadows(token.mix());
```

### Expected results

Could be ok.

### Actual results

Then we found that an error.
```
The argument type 'BoxShadowListMixRef' can't be assigned to the parameter type 'List'. dart[argument_type_not_assignable](https://dart.dev/diagnostics/argument_type_not_assignable)
```

### Code sample

Code sample

```dart
final token = BoxShadowToken('effect');
BoxStyler().boxShadows(token.mix());
```