Fixing cases that requires quotes in pubspecLock

• Added two more cases that requires quotes in pubspecLock files
• Removed deprecated lint rule (invariant_booleans)

Rewrite for output correctness and beautification

• Complete rewrite of YAML formatter
• Correct handling of nested structures
• Built-in automatic beautifier
• Improved support of Dart pubspec file formats with dedicated test suites

Null safety

2.0.0

Migration to null safety

Better compliance to pub.dev quality requirements

• Migration to Dart 2.10
• Code checks against recently introduced dart linter rules
• Better compliance to pub.dev quality requirements

Correct rendering of JSON entries without value

1.0.1

Release 1.0.1 preps

Initial release supporting pubspec.yaml and pubspec.lock formatting styles

1.0.0

Preparations for the initial release (example, readme, etc.)