[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at d7186fe [MemCpyOpt] Add lifetime may alias test (NFC)
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   d7186fe..be6e8e5  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to be6e8e50f4170303e989daea941e8295d9934c66.
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!