[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 1ed2ca6 [flang][driver] Use --match-full-lines in tests for `-test-io`
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   1ed2ca6..b51b424  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to b51b424c679f57dd65d83652f3e62ac2cf6de738.
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!