[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 59c4d5a [SVE] Fix InstCombinerImpl::PromoteCastOfAllocation for scalable vectors
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   59c4d5a..e077367  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to e077367a28102128483f4b2555d2ad31e21b1965.
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!