CMake Deprecation Warning for version < 3.10 starting with CMake 3.31

[oold]

Describe the bug CMake 3.31 emits a deprecation warning.

To Reproduce Steps to reproduce the behavior:

1. Configure project with CMake 3.31.

Expected behavior No deprecation warning is emitted.

Additional context CMake output:

CMake Deprecation Warning at jsoncpp/CMakeLists.txt:17 (cmake_minimum_required):
  Compatibility with CMake < 3.10 will be removed from a future version of
  CMake.

  Update the VERSION argument <min> value.  Or, use the <min>...<max> syntax
  to tell CMake that the project requires at least <min> but has been updated
  to work with policies introduced by <max> or earlier.

Related issue: https://github.com/open-source-parsers/jsoncpp/issues/1521

[StormBytePP]

Since there are related issues to older version I suggest to update the title indicating (<3.10) so it is not confused with the past issues.

[oold]

For reference: https://cmake.org/cmake/help/latest/command/cmake_minimum_required.html#policy-version