[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 1b19015 [X86][AVX] Extend v2f64 BROADCAST(LOAD) -> BROADCAST_LOAD to v2i64/v4f32/v4i32
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   1b19015..04b99a4  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 04b99a4d18cf13c13f1d76c5698696bcaef4e4b6.
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!