science/silo: Backport of patches from Debian to support Python 3

Obtained from: https://salsa.debian.org/science-team/silo-llnl/-/blob/debian/master/debian/patches/python3.patch

		https://salsa.debian.org/science-team/silo-llnl/-/blob/debian/master/debian/patches/python3.8.patch

PR: 249759
Reported by: swills