Revert "Update to latest sync of rust-postgres fork"

This update causes the unsupported_numeric_scale test to fail.

Change-Id: If813164151b1f5e20d47a851fdad4b18ae58776e
Reviewed-on: https://gerrit.readyset.name/c/readyset/+/8458
Reviewed-by: Michael Zink <[email protected]>
Tested-by: Buildkite CI

Author: rs-sac