Bumps [pg](https://github.com/ged/ruby-pg) from 1.5.6 to 1.5.8.
- [Changelog](https://github.com/ged/ruby-pg/blob/master/History.md)
- [Commits](https://github.com/ged/ruby-pg/compare/v1.5.6...v1.5.8)

---
updated-dependencies:
- dependency-name: pg
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>