add back perl-IPC-Cmd for spc-gnu-docker (not included in perl package on aarch64, apparently)

Author: henderkes

src/SPC/doctor/item/LinuxToolCheckList.php

@@ -61,7 +61,8 @@ public function checkCliTools(): ?CheckResult
 
         $required = match ($distro['dist']) {
             'alpine' => self::TOOLS_ALPINE,
-            'redhat', 'centos' => self::TOOLS_RHEL,
+            'redhat' => self::TOOLS_RHEL,
+            'centos' => array_merge(self::TOOLS_RHEL, ['perl-IPC-Cmd']),
             'arch' => self::TOOLS_ARCH,
             default => self::TOOLS_DEBIAN,
         };