[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 219f32f [X86][SSE] Shuffle combine blends to OR(X,Y) if the relevant elements are known zero.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   219f32f..1e392fc  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 1e392fc44584a4909b4dced02b8386b48963002b.
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!