fix: Boost warnings due to deprecations

[paulgessinger]

Had to reopen from #665, because the target branch had changed.

Let's see what this looks like now.

[codecov]

Codecov Report

Merging #880 (ec7d6e1) into main (b14a419) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #880   +/-   ##
=======================================
  Coverage   48.66%   48.66%           
=======================================
  Files         331      331           
  Lines       17129    17129           
  Branches     8094     8094           
=======================================
  Hits         8336     8336           
  Misses       3087     3087           
  Partials     5706     5706           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b14a419...ec7d6e1. Read the comment docs.

[paulgessinger]

The deprecation warning starts in 1.71.0, but there is no direct replacement until 1.72.0. Since this is entirely confined to a single compilation unit, I added a check and up until and including 1.71.0 we'll use the old deprecated header, and starting from 1.72.0 we use the replacement. This means for 1.71.0 the deprecation warning stays visible.

[asalzburger]

Looks fine.