ci: test the configuration that was built

.gitlab/ci/gitlab_ci.cmake

@@ -27,6 +27,7 @@ endif ()
 if (NOT CTEST_BUILD_CONFIGURATION)
   set(CTEST_BUILD_CONFIGURATION "Release")
 endif ()
+set(CTEST_CONFIGURATION_TYPE "${CTEST_BUILD_CONFIGURATION}")
 
 # Default to using Ninja.
 if (NOT "$ENV{CMAKE_GENERATOR}" STREQUAL "")