[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 0f82940 [NFC][flang] Add the header file Todo.h. This file is being upstreamed to satisfy dependencies and enable continued progress on lowering of OpenMP, OpenACC, etc.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   0f82940..d3d790f  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to d3d790fc9827301a49c7bbab3c1eb22da48085c6.
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!