lightdm-enso-os-greeter: fix build with cmake 4 (#450280)

diff --git a/greeter/CMakeLists.txt b/greeter/CMakeLists.txt

index 57aebb0..ab50bff 100644

index 57aebb0..11c4ca7 100644

--- a/greeter/CMakeLists.txt

+++ b/greeter/CMakeLists.txt

@@ -1,6 +1,6 @@

 project (greeter)

-cmake_minimum_required (VERSION 2.8)

-cmake_policy (VERSION 2.8)

+cmake_minimum_required (VERSION 3.10)

+cmake_policy (VERSION 3.10)

 enable_testing ()

@@ -9,7 +9,6 @@ list (APPEND CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/cmake)

 set (CONF_DIR "/etc/lightdm")

 set (DATADIR "${CMAKE_INSTALL_PREFIX}/share")