[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 149f5b5 [APFloat] convert SNaN to QNaN in convert() and raise Invalid signal
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   149f5b5..88f2fe5  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 88f2fe5cad6cc3a3830448cb8a88b52ee449f2d1.
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!