boatswain: add Darwin as broken

Co-authored-by: Anderson Torres <[e-mail]>

pkgs/applications/misc/boatswain/default.nix

···
     license = licenses.gpl3Plus;
     platforms = platforms.unix;
     maintainers = with maintainers; [ _0xMRTT ];
+    broken = stdenv.isDarwin;
   };
 }