[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 16bcd54 AMDGPU/GlobalISel: Mark GlobalISel classes as final
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   16bcd54..0c64233  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 0c64233bb7ae760d36a0af3a22324810787fa4ca.
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!