add docker executable, needed for swarm

flake.nix

@@ -61,6 +61,7 @@
           devShells.default = config.devShells.haskell-package.overrideAttrs (o: {
             nativeBuildInputs = o.nativeBuildInputs or [ ] ++ [
               pkgs.docker-compose
+              pkgs.docker
               pkgs.nixpkgs-fmt
               config.haskellProjects.haskell-package.haskellPackages.releaser
             ];

nix/upstreamable/default.nix

@@ -57,7 +57,7 @@ let
       mv $out/bin/arion $out/libexec
       makeWrapper $out/libexec/arion $out/bin/arion \
         --unset PYTHONPATH \
-        --prefix PATH : ${lib.makeBinPath [ pkgs.docker-compose ]} \
+        --prefix PATH : ${lib.makeBinPath [ pkgs.docker-compose pkgs.docker ]} \
         ;
     '';
   };