[boost] [release] 1.66.0 closed for release

The master branch is now closed for all changes except by permission. The commit-bot isn't running on master, so the super project will need to be manually updated for any changes. If all goes well, the release candidate should be out this weekend. You can still modify the release notes at: https://github.com/boostorg/website/blob/master/feed/history/boost_1_66_0.qb... Thanks, -- The Boost Release Team