[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 87c5437 PDBExtras.h - remove unnecessary raw_ostream forward declaration. NFCI.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   87c5437..d9e191c  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to d9e191cb178afd0ab06f4bc932522ddf2e15ac9e.
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!