Description

So the issue seems to be that flutter_test package cannot work if it's added to the dev_pub helpdependencies and therefore, has to be moved to dev_dependencies.
Since, dev_dependencies wasn't present in pubspec.yaml, I added it

Fixes #132 (issue)

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code of conduct of this project
• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas

• My changes generate no new warnings