[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at e962895 [mlir] [VectorOps] Relaxed restrictions on vector.reduction types even more
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   e962895..e53196b  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to e53196b1e862902c74d83f0ce6f3578b1326f23d.
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!