[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 5911e6a [libc++] Mark a few tests as unsupported on older Clangs to fix bots
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   5911e6a..389ef79  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 389ef79a07850373e2a1f5653d33ce5924bcfe19.
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!