add deprecation warning for CentOS (Stream) 8 (EOL: 2024-05-31)

CentOS 8 stream reached EOL, and we're no longer building packages for it.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

install.sh

@@ -467,7 +467,7 @@ do_install() {
 	# Print deprecation warnings for distro versions that recently reached EOL,
 	# but may still be commonly used (especially LTS versions).
 	case "$lsb_dist.$dist_version" in
-		centos.7|rhel.7)
+		centos.8|centos.7|rhel.7)
 			deprecation_notice "$lsb_dist" "$dist_version"
 			;;
 		debian.buster|debian.stretch|debian.jessie)