RAPIDS switching to CalVer in v0.20 (now v21.06)

Overview

All RAPIDS projects are switching their versioning scheme to Calendar Versioning.

This versioning will apply to both the overall RAPIDS release and each core library, so we will release cuDF 21.06.00, cuML 21.06.00, etc. as part of the overall RAPIDS 21.06.00 release.

Impact

Instead of a 0.20.0 release in June 2021, we will release 21.06.00

New version format for release: YY.MM.PP, for example 21.06.00

New version format for nightlies: YY.MM.PPaYYMMDD, for example 21.06.00a210505

Where PP is the two digit patch number not day.

ABI & API compatibility will be maintained within each YY.MM.xx release.