Merge #164: Bump minimum required cmake to 3.12

729ff16 Bump minimum required cmake to 3.12 (maflcko)

Pull request description:

  This project requires C++20. However, according to https://cmake.org/cmake/help/latest/prop_tgt/CXX_STANDARD.html, the value `20` was only added in cmake 3.12.

  Thus, reflect the reality also in the cmake required minimum version.

  As a side-effect this also avoids a deprecation message when compiling with cmake 3.31, according to https://cmake.org/cmake/help/latest/release/3.31.html#deprecated-and-removed-features

ACKs for top commit:
  hebasto:
    ACK 729ff16.
  hodlinator:
    ACK 729ff16

Tree-SHA512: 4e39a76ff31f22f857302db2dc6501ad0e6d96f1a8ce8bfbe1afd88191cbf11a70b9d4b0cdbb0959a8f601c510cd2aaac3eaa80b78180f1dfce322cad427d79f

Author: ryanofsky

CMakeLists.txt

@@ -2,7 +2,7 @@
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-cmake_minimum_required(VERSION 3.8)
+cmake_minimum_required(VERSION 3.12)
 
 project("Libmultiprocess" CXX)
 if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)