[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at cb1ef0e Follow up rG635b87511ec3: forgot to add/commit the new test file. NFC.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   cb1ef0e..a8d0201  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to a8d02015fcb783d5fdf1e09edd1b9e152c5d19b7.
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!