[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 713c2ad [GlobalISel] Extend not_cmp_fold to work on conditional expressions
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   713c2ad..22fa6b2  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 22fa6b20d92efe796ad881aafe6e689960fe6e7d.
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!