Bump @types/pg from 8.15.4 to 8.15.6

Bumps [@types/pg](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/HEAD/types/pg) from 8.15.4 to 8.15.6.
- [Release notes](https://github.com/DefinitelyTyped/DefinitelyTyped/releases)
- [Commits](https://github.com/DefinitelyTyped/DefinitelyTyped/commits/HEAD/types/pg)

---
updated-dependencies:
- dependency-name: "@types/pg"
  dependency-version: 8.15.6
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Author: dependabot[bot]