Bump flutter from 135454a to b06b8b2 (#148)

Bumps [flutter](https://github.com/flutter/flutter) from `135454a` to `b06b8b2`.
- [Release notes](https://github.com/flutter/flutter/releases)
- [Commits](flutter/flutter@135454a...b06b8b2)

---
updated-dependencies:
- dependency-name: flutter
  dependency-type: direct:production
...

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