[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 793c29a [MLIR,OpenMP][NFCI] Removed loop for accessing regions of ParallelOp
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   793c29a..57bd64f  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 57bd64ff8434aa55aeb1c7a1035f4b5b7468b809.
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!