[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at bdc4c0b Revert "[lldb] avoid assert in threadsanitizer tests on linux"
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   bdc4c0b..ab86e64  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to ab86e64a96624e99df2f2e6183aef5fe7b2a081a.
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!