[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at fe44992 [libc][NFC] For remquo quotient, compare only 3 bits of MPFR and libc results.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   fe44992..2de2ca3  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 2de2ca348dfa09963eb33ddf71c9cbb59612c16a.
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!