build(deps): bump pg from 1.5.7 to 1.5.8 (#7248)

Bumps [pg](https://github.com/ged/ruby-pg) from 1.5.7 to 1.5.8.
- [Changelog](https://github.com/ged/ruby-pg/blob/master/History.md)
- [Commits](ged/ruby-pg@v1.5.7...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]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Gemfile.lock

@@ -276,7 +276,7 @@ GEM
       ast (~> 2.4.1)
       racc
     pdf-core (0.10.0)
-    pg (1.5.7)
+    pg (1.5.8)
     pkg-config (1.5.6)
     pluck_to_hash (1.0.2)
       activerecord (>= 4.0.2)