[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 5a4b2e1 The AssertRecognizer used the module from a frames SC without checking it was non-null.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   5a4b2e1..835c462  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 835c462eae739cf09877597f0c7da43b8aac4bdf.
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!