netsniff-ng: 0.6.3 -> 0.6.4

Semi-automatic update. These checks were performed:

- built on NixOS
- ran `/nix/store/gazzj2la9diafgf11ay2a9pgvvwvjvd2-netsniff-ng-0.6.4/bin/mausezahn help` got 0 exit code
- found 0.6.4 with grep in /nix/store/gazzj2la9diafgf11ay2a9pgvvwvjvd2-netsniff-ng-0.6.4
- found 0.6.4 in filename of file in /nix/store/gazzj2la9diafgf11ay2a9pgvvwvjvd2-netsniff-ng-0.6.4