[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 9d2da67 Revert "[DebugInfo] Emit DW_OP_implicit_value for Floating point constants"
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   9d2da67..557db6f  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 557db6f8aa56dd14803a65aae443d8019b4dcdde.
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!