[CMake] Bump CMake minimum version to 3.13.4

This upgrade should be friction-less because we've already been ensuring
that CMake >= 3.13.4 is used.

This is part of the effort discussed on llvm-dev here:

  http://lists.llvm.org/pipermail/llvm-dev/2020-April/140578.html

Differential Revision: https://reviews.llvm.org/D78648

GitOrigin-RevId: afa1afd4108d973e059e5f5ad68cf01efe7985da
diff --git a/CMakeLists.txt b/CMakeLists.txt
index b50550d..c5b5365 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,7 +2,7 @@
 # Setup Project
 #===============================================================================
 
-cmake_minimum_required(VERSION 3.4.3)
+cmake_minimum_required(VERSION 3.13.4)
 
 if (POLICY CMP0042)
   cmake_policy(SET CMP0042 NEW) # Set MACOSX_RPATH=YES by default