CMake update to quiet warnings

Update the minimum cmake version to 3.16 and set policy CMP0135

Signed-off-by: Eric Kunze <eric.kunze@arm.com>
Change-Id: Idd96c7a318f9458e39d38cd07cf29b9ac6ee63ad
diff --git a/thirdparty/CMakeLists.txt b/thirdparty/CMakeLists.txt
index aa6c43d..df9caee 100644
--- a/thirdparty/CMakeLists.txt
+++ b/thirdparty/CMakeLists.txt
@@ -1,4 +1,6 @@
-cmake_minimum_required (VERSION 3.4)
+cmake_minimum_required (VERSION 3.16)
+
+cmake_policy(SET CMP0135 NEW)
 
 # fetch 3rd party libraries
 include(FetchContent)