[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 0576f43 AMDGPU: Don't sometimes allow instructions before lowered si_end_cf
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   0576f43..2b1cb6d  master     -> origin/master
Auto packing the repository for optimum performance. You may also
run "git gc" manually. See "git help gc" for more information.
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 2b1cb6d54a3298204e01a2982e3d00a1f08743a2.
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!