[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 2d35092 [DWARFYAML] Make the include_directories, file_names and opcodes fields of the line table optional.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   2d35092..455ca0e  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 455ca0ebb69210046928fedffe292420a30f89ad.
CMake Error at CMakeLists.txt:3 (cmake_minimum_required):
  CMake 3.13.4 or higher is required.  You are running version 3.7.1


-- Configuring incomplete, errors occurred!