build: require at least CMake 3.31 for test_package

Author: mpusz

test_package/CMakeLists.txt

@@ -20,7 +20,7 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 # SOFTWARE.
 
-cmake_minimum_required(VERSION 3.25)
+cmake_minimum_required(VERSION 3.31)
 project(test_package LANGUAGES CXX)
 
 message(STATUS "MP_UNITS_BUILD_CXX_MODULES: ${MP_UNITS_BUILD_CXX_MODULES}")