.gitlab-ci: Add centos9 image

Signed-off-by: Norbert Pocs <npocs@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
(cherry picked from commit 84df28ee31)

.gitlab-ci.yml

@@ -2,6 +2,7 @@
 variables:
   BUILD_IMAGES_PROJECT: libssh/build-images
   CENTOS7_BUILD: buildenv-centos7
+  CENTOS9_BUILD: buildenv-c9s
   COVERITY_BUILD: buildenv-coverity
   FEDORA_BUILD: buildenv-fedora
   MINGW_BUILD: buildenv-mingw
@@ -77,6 +78,14 @@ centos7/openssl_1.0.x/x86_64:
       make -j$(nproc) &&
       ctest --output-on-failure
 
+centos9s/openssl_3.0.x/x86_64:
+  image: $CI_REGISTRY/$BUILD_IMAGES_PROJECT:$CENTOS9_BUILD
+  extends: .tests
+  script:
+    - cmake3 $CMAKE_OPTIONS .. &&
+      make -j$(nproc) &&
+      ctest --output-on-failure
+
 
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 #                               Fedora builds                                 #