[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 85fce44 [Sema] Simplify ShouldDiagnoseUnusedDecl, NFC
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   85fce44..6ce5b74  master     -> origin/master
Auto packing the repository for optimum performance. You may also
run "git gc" manually. See "git help gc" for more information.
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 6ce5b74b82ab4667dde688860f2d3a7be88e46da.
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!