[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at c70f0b9 [SCEVExpander] Avoid re-using existing casts if it means updating users.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   c70f0b9..43bdac2  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 43bdac290663f4424f9fb3920c47c7288a2aabb4.
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!