[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 3052e47 [InstCombine] matchBSwapOrBitReversem - recognise or(fshl(),fshl()) bswap patterns.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   3052e47..d64ea0f  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to d64ea0f18994e06c4428548c4093b3ce7a35cb98.
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!