Update deps to remove warning (#226)

When running `poetry install --no-root` locally, I noticed a warning:

> Warning: The lock file is not up to date with the latest changes in
> pyproject.toml. You may be getting outdated dependencies. Run update
> to update them.

Instead of running that command though, I ran `poetry lock --no-update`
to regenerate the lockfile. Then I ran `poetry install --no-root` again,
which resulted in the following updates:

> Updating coverage (6.4.3 -> 6.4.4)
> Updating uvicorn (0.18.2 -> 0.18.3)

Author: grahamalama