website: Drop support for Python2. Python3.6+ min version

Issue-on: https://gem5.atlassian.net/browse/GEM5-818
Change-Id: I3eff88f1f13168d9069449d1bc6d94105cc2ea5d
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5-website/+/43805
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: Bobby R. Bruce <bbruce@ucdavis.edu>
2 files changed