misc: Updated version to 20.1.0.0

Change-Id: Ic7a37581c58caa354eeecab051122116177d0721
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/35456
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
3 files changed