[release][multi_index] permission to merge to master

From: Joaquin M López Muñoz (joaquinlopezmunoz_at_[hidden])
Date: 2022-04-03 13:11:28

Hi, the following PR is absolutely trivial

https://github.com/boostorg/multi_index/pull/57

but seems like it's important to Bitcoin guys in connection with an 
effort to prune internal Boost dependencies they're carrying out.

Can I merge to master or should I wait till Boost 1.80?

Thank you,

Joaquín M López Muñoz