There's a merged pull request on the void-packages repository

boost: new distfiles location
https://github.com/void-linux/void-packages/pull/31899

Description:
Download location documented to replace the old, non-working one:

https://www.boost.org/users/news/boost_has_moved_downloads_to_jfr.html
>> Instead of: https://dl.bintray.com/boostorg/release/ you should use https://boostorg.jfrog.io/artifactory/main/release/ to retrieve boost releases.

Tested availability of  the present version:
$ curl -I https://boostorg.jfrog.io/artifactory/main/release/1.72.0/source/boost_1_72_0.tar.bz2 2>&1|egrep Date\|256
Date: Sat, 10 Jul 2021 21:30:24 GMT
X-Checksum-Sha256: 59c9b274bc451cf91a9ba1dd2c7fdcaf5d60b1b3aa83f2c9fa143417cc660722

#### General
- [ ] This is a new package and it conforms to the [quality requirements](https://github.com/void-linux/void-packages/blob/master/Manual.md#quality-requirements)

#### Have the results of the proposed changes been tested?
- [ ] I use the packages affected by the proposed changes on a regular basis and confirm this PR works for me
- [x] I generally don't use the affected packages but briefly tested this PR

[skip ci] no package change expected, only the distribution location for future builds

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