[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 7c71b44 [InstCombine] Remove accidental unnecessary ConstantExpr qualification added in rGb752daa26b64155
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   7c71b44..c7f3bc8  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to c7f3bc87d3e5442bfbbb08133e3cc634d6ae466f.
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!