base: Update the version to v21.2.0.0

Change-Id: Ib4b3d0a370498c59d6b56701bfa5018d8c1cb709
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/54464
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
2 files changed