Semi-automatic update. These checks were done:
- built on NixOS
- ran `/nix/store/vh158gs5y12g1rdd1dhbd1ng2mz1761s-haproxy-1.8.4/bin/haproxy -v` and found version 1.8.4
- found 1.8.4 with grep in /nix/store/vh158gs5y12g1rdd1dhbd1ng2mz1761s-haproxy-1.8.4
- found 1.8.4 in filename of file in /nix/store/vh158gs5y12g1rdd1dhbd1ng2mz1761s-haproxy-1.8.4