[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at ce0eb81 [UpdateTestChecks] Allow $ in function names
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   ce0eb81..c57df3d  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to c57df3dc09e8b59c55c83ba5c354569a82a5c3b8.
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!