[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 11d2e63 [analyzer][StdLibraryFunctionsChecker] Separate the signature from the summaries
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   11d2e63..d4035af  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to d4035af2537432da41b2728829f8cd2fca9a9de8.
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!