Bump pg from 1.5.5 to 1.5.6 (#512)

Bumps [pg](https://github.com/ged/ruby-pg) from 1.5.5 to 1.5.6.
- [Changelog](https://github.com/ged/ruby-pg/blob/master/History.md)
- [Commits](https://github.com/ged/ruby-pg/compare/v1.5.5...v1.5.6)

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

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Gemfile.lock

@@ -246,7 +246,7 @@ GEM
     parser (3.3.0.5)
       ast (~> 2.4.1)
       racc
-    pg (1.5.5)
+    pg (1.5.6)
     prism (0.24.0)
     propshaft (0.8.0)
       actionpack (>= 7.0.0)