[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 3e5b8d8 [AArch4] Regenerate test checks for f16-imm.ll. NFC
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   3e5b8d8..0dd8782  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 0dd87825db2e73c2fb538f710217673ac15b7255.
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!