Bump pg from 1.6.2 to 1.6.3

Bumps [pg](https://github.com/ged/ruby-pg) from 1.6.2 to 1.6.3.
- [Changelog](https://github.com/ged/ruby-pg/blob/master/CHANGELOG.md)
- [Commits](ged/ruby-pg@v1.6.2...v1.6.3)

---
updated-dependencies:
- dependency-name: pg
  dependency-version: 1.6.3
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]