gitlab: fix s390x tag for avocado-system-centos

The 390x tag should be s390x.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Message-ID: <20240107170119.82222-2-npiggin@gmail.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>

.gitlab-ci.d/buildtest.yml

@@ -184,7 +184,7 @@ avocado-system-centos:
   variables:
     IMAGE: centos8
     MAKE_CHECK_ARGS: check-avocado
-    AVOCADO_TAGS: arch:ppc64 arch:or1k arch:390x arch:x86_64 arch:rx
+    AVOCADO_TAGS: arch:ppc64 arch:or1k arch:s390x arch:x86_64 arch:rx
       arch:sh4 arch:nios2
 
 build-system-opensuse: