[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at e5766f2 Use uint64_t for branch weights instead of uint32_t
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   e5766f2..c6ca26c  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to c6ca26c0bfedb8f80d6f8cb9adde25b1d6aac1c5.
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!