[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 97866b8d [ThinLTO][Legacy] Fix StringRef assertion from ThinLTO bots
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   97866b8d..b3e1394 master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to b3e139444f41e5c281972b4002c09ee0500831f6.
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!