Bump cmake_minimum_required for CMake 4 compatibility.

CMake 4 dropped compatibility with cmake_minimum_required() versions below
3.5, so the 0.0.1 tarball (VERSION 3.4.3) can no longer be configured with
the CMake in the tree. Upstream fixed this on the main branch in PR #120;
use a range form here so the 0.0.1 release keeps building.

https://github.com/lldb-tools/lldb-mi/pull/120

--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.4.3)
+cmake_minimum_required(VERSION 3.5...3.20)

 if(POLICY CMP0077)
   cmake_policy(SET CMP0077 NEW)