[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at e6f3ec6 Don't link any LLVM/MLIR library to the C API unit-test
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   e6f3ec6..3897137  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 3897137598128e64c246a6a604f948fa4e9a5db7.
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!