Bump postgres from 0.19.11 to 0.19.12

Bumps [postgres](https://github.com/rust-postgres/rust-postgres) from 0.19.11 to 0.19.12.
- [Release notes](https://github.com/rust-postgres/rust-postgres/releases)
- [Commits](rust-postgres/rust-postgres@postgres-v0.19.11...postgres-v0.19.12)

---
updated-dependencies:
- dependency-name: postgres
  dependency-version: 0.19.12
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]