build(deps-dev): Bump pg from 8.20.0 to 8.21.0

Bumps [pg](https://github.com/brianc/node-postgres/tree/HEAD/packages/pg) from 8.20.0 to 8.21.0.
- [Changelog](https://github.com/brianc/node-postgres/blob/master/CHANGELOG.md)
- [Commits](https://github.com/brianc/node-postgres/commits/pg@8.21.0/packages/pg)

---
updated-dependencies:
- dependency-name: pg
  dependency-version: 8.21.0
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]