Bump pghero from 2.7.3 to 2.7.4 (#15668)

Bumps [pghero](https://github.com/ankane/pghero) from 2.7.3 to 2.7.4.
- [Release notes](https://github.com/ankane/pghero/releases)
- [Changelog](https://github.com/ankane/pghero/blob/master/CHANGELOG.md)
- [Commits](https://github.com/ankane/pghero/compare/v2.7.3...v2.7.4

)

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