Add dagster-dg to make install dev script

[gibsondan]

Summary & Motivation

Include dagster-dg in the dagster local dev environment.

How I Tested These Changes

Run make dev command locally

Changelog

NOCHANGELOG

[smackesey]

I actually think we should avoid this because dg is supposed to run in an isolated environment and may hard-pin dependencies (it already does with typer). Preferred way to dev with dg is uv tool install -e /path/to/dagster-dg.