Enable Apple linker library deduplication

CMake 3.29 introduced policy CMP0156
(https://cmake.org/cmake/help/v3.29/policy/CMP0156.html) allowing to
avoid linker warnings such as

  ld: warning: ignoring duplicate libraries: '-ldl', '-lm', 'lib/libceres.a', 'lib/libgtest.a'

Fixes #1010

Change-Id: I6c3cf15382c5de4c005bcb28ac6931196f00fe48

CMakeLists.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8b0ce47..aa27929 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -29,7 +29,7 @@
 # Authors: keir@google.com (Keir Mierle)
 #          alexs.mac@gmail.com (Alex Stewart)
 
-cmake_minimum_required(VERSION 3.16...3.27)
+cmake_minimum_required(VERSION 3.16...3.29)
 project(Ceres C CXX)
 
 # NOTE: The following CMake variables must be applied consistently to all