[CMake] VERSION_GREATER_EQUAL is not avail. before CMake 3.7.

CMakeLists.txt

@@ -64,7 +64,7 @@ if(OGS_BUILD_GUI)
     add_definitions(-DOGS_BUILD_GUI)
     # TODO: Remove when this is fixed in CMake, maybe in 3.10
     # https://gitlab.kitware.com/cmake/cmake/issues/17205
-    if(${CMAKE_VERSION} VERSION_GREATER_EQUAL 3.9.0)
+    if(${CMAKE_VERSION} VERSION_GREATER 3.8.2)
         message(FATAL_ERROR "OGS_BUILD_GUI is not supported with CMake 3.9.x. Please downgrade CMake to 3.8.x!")
     endif()
 endif()