[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at f80866b [flang] Make -fget-symbols-sources output deterministic
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   f80866b..8d2d0e8  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 8d2d0e84857cb1f2d01456eb433b5172d3a0772b.
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!