[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 0b1b2a1 [llvm-objdump][test] Delete source-interleave-prefix-windows.test
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   0b1b2a1..874524a  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 874524ab88a9cb8a9208be281ab5103c92b8bf15.
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!