[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 41c9f4c [LoopVectorize] NFC: Fix unused variable warning for MaxSafeDepDist
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   41c9f4c..5911e6a  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 5911e6a8857f146fb5a8f23af1d768aba25e7c3e.
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!