[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at e7f5304 [Test] Move IndVars test to a proper place
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   e7f5304..ffd0b31  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to ffd0b31c7cbaa8322d2963afe6ace4e3a0889ddb.
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!