Bump annotations from 20.1.0 to 21.0.0

Bumps [annotations](https://github.com/JetBrains/java-annotations) from 20.1.0 to 21.0.0.
- [Release notes](https://github.com/JetBrains/java-annotations/releases)
- [Changelog](https://github.com/JetBrains/java-annotations/blob/master/CHANGELOG.md)
- [Commits](https://github.com/JetBrains/java-annotations/compare/20.1.0...21.0.0

)

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