[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 8e8cc58 [NFC][AMDGPU] Reorder SIMemoryLegalizer functions to be consistent
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   8e8cc58..de1016c  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to de1016ce5cdca2df51c00fbc5d3a750d5d72364a.
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!