ci: remove centos8 support

due to centos8 EOL

.github/workflows/build_packages.yaml

@@ -264,7 +264,6 @@ jobs:
           - debian10
           - debian9
           # - opensuse
-          - centos8
           - centos7
           - raspbian10
           # - raspbian9
@@ -303,7 +302,7 @@ jobs:
             elixir: 1.13.2
             build_elixir: with_elixir
             arch: amd64
-            os: centos8
+            os: centos7
             build_machine: ubuntu-20.04
 
     defaults:

build

@@ -202,9 +202,6 @@ make_docker_testing() {
             ubuntu20*)
                 EMQX_BASE_IMAGE="ubuntu:20.04"
                 ;;
-            centos8)
-                EMQX_BASE_IMAGE="centos:8"
-                ;;
             *)
                 echo "Unsupported testing base image for $SYSTEM"
                 exit 1

scripts/get-distro.sh

@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 
 ## This script prints Linux distro name and its version number
-## e.g. macos, centos8, ubuntu20.04
+## e.g. macos, centos7, ubuntu20.04
 
 set -euo pipefail