[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at f5fe7ab [VPlan] Account for removed users in replaceAllUsesWith.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   f5fe7ab..b4288f2  master     -> origin/master
Auto packing the repository for optimum performance. You may also
run "git gc" manually. See "git help gc" for more information.
First, rewinding head to replay your work on top of it...
Fast-forwarded master to b4288f278a254e597295001f7e544b680b54e61a.
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!