[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at eb2a405 [NFC] [DAGCombiner] Remove unnecessary negation in visitFNEG
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   eb2a405..bc3d4d9  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to bc3d4d9ed783a3051125075f1a58ad619d8ea454.
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!