[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at e74e8b2 [NFC][InstCombine] Add tests for PHI merging/aggregate reconstruction (PR47060)
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   e74e8b2..df79e18  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to df79e18796d09f33d15974c55cca8b2b5b484e1f.
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!