overmind socket not set when using devenv in flake

[jonknapp]

Describe the bug
While overmind is present in the cli, running any of its commands (like overmind connect web) fails to connect since it's expecting .overmind.sock to exist by default. I believe this was introduced with this commit.

To reproduce

# example flake
{
  inputs = {
    devenv = {
      url = "github:cachix/devenv";
      inputs.nixpkgs.follows = "nixpkgs";
    };
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    systems.url = "github:nix-systems/default";
  };

  outputs = { self, devenv, nixpkgs, systems, ... } @ inputs:
    let
      forEachSystem = nixpkgs.lib.genAttrs (import systems);
    in
    {
      # https://github.com/cachix/devenv/issues/756
      packages = forEachSystem (system: {
        devenv-up = self.devShells.${system}.default.config.procfileScript;
      });
      devShells = forEachSystem
        (system:
          let
            pkgs = import nixpkgs {
              inherit system;
            };
          in
          {
            default = devenv.lib.mkShell {
              inherit inputs pkgs;
              modules = [
                {
                  name = "app";

                  # env.OVERMIND_SOCKET = "./.devenv/run/overmind.sock";

                  process.implementation = "overmind";
                  processes = {
                    one.exec = "sleep 100";
                  };
                }
              ];
            };
          });
    };
}

1. Start it with devenv up
2. Open a new terminal window and run overmind status
3. You'll see something like overmind: dial unix ./.overmind.sock: connect: no such file or directory instead of the command output if you would have specified the path to overmind's socket at .direnv/run/overmind.sock

Version

devenv: 1.0.7 and I'm using flakes.

Workaround

If I specify something like env.OVERMIND_SOCKET = "./.devenv/run/overmind.sock"; in my devenv config, it will then allow overmind commands to use the correct socket.