[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 2e15f4a [pstl] Replace direct use of assert() with _PSTL_ASSERT
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   2e15f4a..04776bd  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 04776bd0ed50bfeac3b10ce85e6edf1abad390bb.
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!