[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at c413a8a [LoopLoadElim] Filter away candidates that stop being AddRecs after loop versioning. PR47457
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   c413a8a..3c42c0d  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 3c42c0dcf631ad6b90e718df895c05f79718659f.
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!