In a discussion a year ago [1], I proposed dropping versioned libs
subpackages and the consensus was that the versioning should be kept.
Since then, protobuf has been updated several times and we've always
been able to migrate all dependants, so there's no need to keep the
versioned packages around just in case that can't happen some day.
Let's drop the versioned packages to make upgrades easier and avoid
polluting repo indexes with old packages that don't get cleaned. Users
who need old versions of the libs for un-packaged software may need to
build those old versions by hand, but this is just one of the pitfalls
of using a rolling Linux distribution.
[1]: https://github.com/void-linux/void-packages/pull/18691
f38a742bec