chore(deps): bump tokio-postgres in /reference-apps/rust

Bumps [tokio-postgres](https://github.com/rust-postgres/rust-postgres) from 0.7.15 to 0.7.16.
- [Release notes](https://github.com/rust-postgres/rust-postgres/releases)
- [Commits](rust-postgres/rust-postgres@tokio-postgres-v0.7.15...tokio-postgres-v0.7.16)

---
updated-dependencies:
- dependency-name: tokio-postgres
  dependency-version: 0.7.16
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Author: dependabot[bot]