Adaptor the widget_driver_generator for dart workspace

[LongXiangGuo]

Describe the bug
When generate file in child package, it could not locate the pubspec.lock

To Reproduce
Steps to reproduce the behavior, e.g.:

1. Create new Driver
2. Create new DrivableWidget using the driver
3. Use widget in a build method
4. Trying to get data from driver
5. See error

Expected behavior
A clear and concise description of what you expected to happen.

Screenshots
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System info (please complete the following information):

• Flutter version: [e.g. 3.3.9]
• widget_driver version: [e.g. 1.2.3]
• OS & version: [e.g. iOS 16.0]

Additional context
Add any other context about the problem here.

[4ndrey]

Fixed in #183