[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 7ad6ea5 [DWARFYAML][debug_aranges] Use yaml::Hex64 rather than uint64_t as length. NFC.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   7ad6ea5..dcdc776  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to dcdc77619e1af61181e7214d292b7e5b59946186.
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!