[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 98ef7e2 This reduces code duplication between CGObjCMac.cpp and Mangle.cpp
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   98ef7e2..4c19b89  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 4c19b89b2587f321e1014a9855973c08a822b908.
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!