[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 8e06bf6 [Polly] Ensure consistent Scop::InstStmtMap. NFC.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   8e06bf6..5d8eede  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 5d8eedee917de2d39d1c485d07a30f8649bc6866.
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!