[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 3221c24 Fix update_llc_test_checks function regex for RV64
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   3221c24..4d90ff5  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 4d90ff59ac453a67ac692ffdf8242e4cfbd2b34f.
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!