[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 0fc1aa2 Updating llvm.mlir test to match recent IR change
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   0fc1aa2..f067bc3  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to f067bc3c0ad6b8800f63066d654ad15c3dd33fd1.
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!