[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 38b632c [ELF] --gdb-index: support --icf={safe,all}
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   38b632c..729d7d2  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 729d7d23282e9b00eaa7a5f35a4224929d73d3a4.
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!