gem5 version 20.0.0.3
misc: Updated release notes and version number

Updated the release notes and version number for the v20.0.0.3
hot-fix.

Change-Id: I3fe8eda1e6859f76a91fbcee595426bd25bfe432
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/30956
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