Set CMake Policy CMP0167 to OLD.

NEW disables Cmake's FindBoost in favor of Boost's built-in
BoostConfig.cmake introduced in Boost 1.70.

CMakeLists.txt

@@ -6,6 +6,11 @@ cmake_minimum_required (VERSION 3.14.5)
 if (POLICY CMP0094)
   cmake_policy(SET CMP0094 NEW)
 endif()
+# CMake 3.30+ Use Boost's builtin BoostConfig.cmake instead of FindBoost, the latter of which is removed. Stting this policy to OLD temporarily restores it. BoostConfig.cmake was introduced in Boost 1.70.
+# A fair number of distros are still shipping Boost 1.69 in "legacy" versions so make it OLD for the 5.x series and NEW for 6.x.
+if (POLICY CMP0167)
+  cmake_policy(SET CMP0167 OLD)
+endif()
 
 project (gnucash
     VERSION 5.8