[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 4b14ef3 Temporarily Revert "Unify the return value of GetByteSize to an llvm::Optional<uint64_t> (NFC-ish)"
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   4b14ef3..595d214  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 595d214f47e484ffe517a4294d3ac042d6c7d25d.
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!