[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at b2fa3b9 [lldb] Make GetSelectedOrDummyTarget return the target by reference (NFC)
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   b2fa3b9..e84c3b2  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to e84c3b2fc82806a7f2f6ec466f08da94ea650198.
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!