hound, nixos/hound: deduplicate runtime deps

nixos/modules/services/search/hound.nix

···
                     " -conf ${pkgs.writeText "hound.json" cfg.config}";
 
       };
-      path = [ pkgs.git pkgs.mercurial pkgs.openssh ];
     };
   };
 

pkgs/development/tools/misc/hound/default.nix

···
 , makeWrapper
 , mercurial
 , git
+, openssh
 , nixosTests
 }:
 
···
   doCheck = false;
 
   postInstall = ''
-    wrapProgram $out/bin/houndd --prefix PATH : ${lib.makeBinPath [ mercurial git ]}
+    wrapProgram $out/bin/houndd --prefix PATH : ${lib.makeBinPath [ mercurial git openssh ]}
   '';
 
   passthru.tests = { inherit (nixosTests) hound; };