bump CMake minimum version for CMake 4
diff --git a/CMakeLists.txt b/CMakeLists.txt
index c23f7fa..53104f6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -11,8 +11,8 @@
 # of their own GPLv2 license and all copyright is transferred to them for
 # all posterity and eternity, wherever such transfer is possible.  Where it is
 # not, then this file is released under the GPLv2 by myself.
+CMAKE_MINIMUM_REQUIRED(VERSION 3.10.0)
 PROJECT(libsword CXX C)
-CMAKE_MINIMUM_REQUIRED(VERSION 2.6.0)
 SET(SWORD_VERSION 1.9.0)
 
 # Make sure it's an out-of-stream build