haproxy: 1.7.2 -> 1.7.3

[fuzzy-id]

Motivation for this change

Update

Things done

• Tested using sandboxing
  (nix.useSandbox on NixOS,
  or option build-use-sandbox in nix.conf
  on non-NixOS) (executed: nix-build --option build-use-sandbox true ~/src/nixpkgs -A haproxy
• Built on platform(s)
  • NixOS
  • macOS
  • Linux
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip" (looks like there are no dependencies)
• Teted execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.

---

[mention-bot]

@fuzzy-id, thanks for your PR! By analyzing the history of the files in this pull request, we identified @garbas, @pmahoney and @rbvermaa to be potential reviewers.