[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at f9ad112 [lldb] Speed up TestValueObjectRecursion by making it a no_debug_info_test
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   f9ad112..740625fe master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 740625fecd1a4cd8e5521bd1c98627eca6f7565d.
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!