[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 97b351a [mlir][gpu] Fix leaked stream and module when lowering gpu.launch_func to runtime calls.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   97b351a..20a3931  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 20a3931f8fadb9c13b4868d1b0124498b014b1d5.
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!