Bump github.com/mitchellh/mapstructure from 1.1.2 to 1.4.2 in /api

Bumps [github.com/mitchellh/mapstructure](https://github.com/mitchellh/mapstructure) from 1.1.2 to 1.4.2.
- [Release notes](https://github.com/mitchellh/mapstructure/releases)
- [Changelog](https://github.com/mitchellh/mapstructure/blob/master/CHANGELOG.md)
- [Commits](https://github.com/mitchellh/mapstructure/compare/v1.1.2...v1.4.2

)

---
updated-dependencies:
- dependency-name: github.com/mitchellh/mapstructure
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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