unbound: Vendor import 1.19.3
Release notes at
https://www.nlnetlabs.nl/news/2024/Mar/14/unbound-1.19.3-released/
Merge commit '5a33598e88ad8fbc0affa74dee0a2d8cc4010fbc' into main
(cherry picked from commit b7c0c8c18e0f12bc22e251fbcabad719b364a38a)