[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at cb6e693 NFC: [GVNHoist] Hoist loop invariant code and rename variables for readability
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   cb6e693..6dabd26  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 6dabd267bd70ee86f47d08faa027ade169f3e330.
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!