[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 973800d Revert "[MLIR][Shape] Merge `shape` to `std`/`scf` lowerings."
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   973800d..4b530f7  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 4b530f75199d9b5e7ee1f4e86e1513a83b4b86cb.
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!