build: update conan test to C++20

conan/test_package/CMakeLists.txt

@@ -1,9 +1,9 @@
-cmake_minimum_required(VERSION 3.7.2)
+cmake_minimum_required(VERSION 3.12.4)
 project(test_package)
 
 set(CMAKE_VERBOSE_MAKEFILE TRUE)
 
-set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
 include(${CMAKE_BINARY_DIR}/conanbuildinfo.cmake)