[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at d8bb30c [yaml2obj] - Allow specifying no tags to create empty sections in few cases.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   d8bb30c..d7fa903  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to d7fa9030d47fa62ad443717f4d1c8da4096a1d6c.
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!