[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 64435a4 [DWARFYAML][test] Simplify __debug_pubnames/types tests. NFC.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   64435a4..61ac58e  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 61ac58e10ae1fbb18416cac20119725803b9ad6f.
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!