[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 21c165d [CMake] Pass bugreport URL to standalone clang build
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   21c165d..d3f01b6  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to d3f01b6681bf73b382521db812341e0041787cc9.
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!