chore(deps): update dependency com.google.cloud:google-cloud-spanner to v6.72.0 (#3261)

* chore(deps): update dependency com.google.cloud:google-cloud-spanner to v6.69.0

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>
Co-authored-by: Knut Olav Løite <[email protected]>

Author: 3 people