Support null safety

[IchordeDionysos]

This is a request to add support for null safety to package:flutter_sticky_header.
We depend on your awesome package, so would be great to have null safety enabled.

The Dart/Flutter team already encourages publishing the migrated packages: See this blog post.

See the migration guide for details about enabling null safety.

[IchordeDionysos]

Blocked by letsar/value_layout_builder#3

[IchordeDionysos]

The new Dart version with null-safety was just released 😍
https://medium.com/dartlang/announcing-dart-2-12-499a6e689c87

[zs-dima]

Any updates on this issue are welcome

[ThexXTURBOXx]

Workaround, use this version here:

  flutter_sticky_header:
    git:
      url: https://github.com/Femtopedia/flutter_sticky_header.git
      ref: temp

[ThexXTURBOXx]

@innwin I accidentally pushed some local changes I wanted to push in the near future. Give me a minute, I will create a new branch with some temporary stuff

[ThexXTURBOXx]

@innwin and all others here: I added a new branch. Use this one now: #57 (comment)