TIL: Loading .env files with uv run

We don't need python-dotenv, use uv run with --env-file, and your env vars from .env get loaded.

For example, if we've got a FastAPI or Air project we can run it locally with env vars like:

uv run --env-file .env fastapi dev

You can specific different env files for different environments, like .env.dev, .env.prod, etc.

uv run --env-file .env.dev fastapi dev

All credit goes to Audrey Roy Greenfeld for pointing this out.