chore(master): release 2.3.1

[slo-generator-bot]

:robot: I have created a release beep boop

2.3.1 (2022-10-27)

Bug Fixes

• migrate cloud_service_monitoring backend to google-cloud-monitoring v2 (with breaking changes) (#280) (affd157)

Documentation

• document Cloud Monitoring MQL backend (#277) (8c931cd)
• refine development workflow instructions (#275) (2a35754)

---

This PR was generated with Release Please. See documentation.

[slo-generator-bot]

:robot: Release is at https://github.com/google/slo-generator/releases/tag/v2.3.1 :sunflower: