[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at e72d792 Guard `find_library(tensorflow_c_api ...)` by checking for TENSORFLOW_C_LIB_PATH to be set by the user
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   e72d792..665dc40  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 665dc4012b65589618cc1b22f44f1e59e021145c.
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!