[libxml2] gitlab-ci: Fix tar invocation

[Nick Wellnhofer <nwellnhof src gnome org>]

commit ae98a5b47e0a10937af746147b758f16a52f1252
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Wed Sep 7 12:10:39 2022 +0200

    gitlab-ci: Fix tar invocation

 .gitlab-ci/setup_mingw.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/.gitlab-ci/setup_mingw.sh b/.gitlab-ci/setup_mingw.sh
index 5168c2d1..e2a1e868 100644
--- a/.gitlab-ci/setup_mingw.sh
+++ b/.gitlab-ci/setup_mingw.sh
@@ -13,5 +13,5 @@ done
 if [ ! -e libxml2-build/xmlconf ]; then
     mkdir -p libxml2-build
     wget https://www.w3.org/XML/Test/xmlts20080827.tar.gz -O - |
-       tar -C libxml2-build x
+       tar -x -z -C libxml2-build
 fi