Bump class-transformer from 0.2.3 to 0.3.1

Bumps [class-transformer](https://github.com/typestack/class-transformer) from 0.2.3 to 0.3.1.
- [Release notes](https://github.com/typestack/class-transformer/releases)
- [Changelog](https://github.com/typestack/class-transformer/blob/develop/CHANGELOG.md)
- [Commits](typestack/class-transformer@v0.2.3...v0.3.1)

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Author: dependabot[bot]