[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 16580d7 Remove -gen-pass-doc from Flang CMake configuration: the documentation generation is broken
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   16580d7..efd8c9e  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to efd8c9ed726df5376ca8ac3ddc75ab91a40dd873.
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!