[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 9c7b0c4 [MLIR] Add PatternRewriter::mergeBlockBefore() to merge a block in the middle of another block.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   9c7b0c4..b690c11  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to b690c1157e90b67ecd8f03b902c452ad13defb6f.
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!