Unnecessary import blocking publishing action

[flaviumarinescu]

Please approve to unblock publishing action

########## Publish Log

Package validation found the following potential issue:

• dart analyze found the following issue(s): Analyzing lib, pubspec.yaml...

  info - lib/src/chart_painter.dart:4:8 - The import of 'package:flutter/widgets.dart' is unnecessary because all of the used elements are also provided by the import of 'package:flutter/material.dart'. Try removing the import directive. - unnecessary_import

  1 issue found.

Package has 1 warning. pub finished with exit code 65

[flaviumarinescu]

@h65wang , please :D