Removed centos:7 image from package_build_rules because mirrorlist.centos.org is no longer available

Removed ubuntu:xenial image from package_build_rules because its GLIBC is too old to support Node 20 required by GitHub Actions

Removed ubuntu:bionic image from package_build_rules because its GLIBC is too old to support Node 20 required by GitHub Actions

Removed debian:stretch image from package_build_rules because its GLIBC is too old to support Node 20 required by GitHub Actions

Removed debian:stretch image from package_test_rules because the LXC/Incus image no longer exists

Removed ubuntu:bionic image from package_test_rules because the LXC/Incus image no longer exists

Removed centos:7 image from package_test_rules because Ploutos no longer supports building for CentOS 7

Removed ubuntu:xenial image from package_test_rules because the LXC/Incus image no longer exists