[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at ab86e64 [DSE] Remove some dead code from DSE tests.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   ab86e64..f9ad112  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to f9ad112770ece2e3612ddcdd6a4157bc0b0faf31.
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!