AoS_2, earth demo: find_package(nlohmann_json...) must be QUIET (#8220)

## Summary of Changes

Fix after #7678 was merge in `master`. There was an worrying CMake
warning.

## Release Management

* Affected package(s): Arr_2

Arrangement_on_surface_2/demo/Arrangement_on_surface_2_earth/CMakeLists.txt

@@ -14,7 +14,7 @@ endif()
 
 find_package(Qt6 QUIET COMPONENTS Core Gui OpenGL OpenGLWidgets Widgets Xml)
 find_package(CGAL COMPONENTS Qt6)
-find_package(nlohmann_json 3.9)
+find_package(nlohmann_json QUIET 3.9)
 
 if (NOT CGAL_FOUND OR NOT CGAL_Qt6_FOUND OR NOT Qt6_FOUND OR NOT Boost_FOUND OR NOT nlohmann_json_FOUND)
   if (NOT CGAL_FOUND)
@@ -33,7 +33,7 @@ if (NOT CGAL_FOUND OR NOT CGAL_Qt6_FOUND OR NOT Qt6_FOUND OR NOT Boost_FOUND OR
     set(MISSING_DEPS "JSON for Modern C++ 3.9+ (know as nlohmann_json), ${MISSING_DEPS}")
   endif()
 
-  message(STATUS "This project requires ${MISSING_DEPS} and will not be compiled.")
+  message(STATUS "NOTICE: This project requires ${MISSING_DEPS} and will not be compiled.")
   return()
 endif()