[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at be2bc7d [SyntaxTree] Update `Modifiable` tests to dump `NodeRole` and `unmodifiable` tag
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   be2bc7d..cdd339c  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to cdd339c568fdd0fa2494745d0f661c4a0647c13c.
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!