libdsm >=1.0.0 which doesn't support null safety

[swithun-liu]

The current Dart SDK version is 3.2.0.

Because x_plore_remote_ui depends on libdsm >=1.0.0 which doesn't support null safety, version solving failed.

The lower bound of "sdk: '>=2.1.0 <3.0.0'" must be 2.12.0 or higher to enable null safety. For details, see https://dart.dev/null-safety Process finished with exit code 1