[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 8d0fdd3 [IR] CmpInst: Add getFlippedSignednessPredicate()
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   8d0fdd3..0c782c2  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 0c782c214b56102161c03ec5657455b7c73a5722.
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!