[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 6c25816 [DSE] Look through memory PHI arguments when removing noop stores in MSSA.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   6c25816..149f5b5  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 149f5b573c79eac0c519ada4d2f7c50e17796cdf.
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!