[boost] [release] 1.67.0 closed for major changes

The master branch is now closed for major changes and will be closed for the beta in a week. Also, you can also add your libraries' changes to the release notes at: https://github.com/boostorg/website/blob/master/feed/history/boost_1_67_0.qb... Remember that after editing the file, you need to submit the form to create a pull request. You can preview the release notes at: http://www.boost.org/users/history/in_progress.html Thanks, -- The Boost Release Team