Revert release version

[vbalani002]

Problem

v10.2.12 release failed midway through the process, and v10.2.12 was not made available on the confluent hub.

Solution

Revert the snapshot version to v10.2.12-SNAPSHOT and re-attempt the release.

[confluent-cla-assistant]

🎉 All Contributor License Agreements have been signed. Ready to merge.
_{Please push an empty commit if you would like to re-run the checks to verify CLA status for all contributors.}