re-lint imports section of test_base_resource.py

This was done by running `pre-commit run --all`. That this was needed
is a temporary glitch in how our `Tests and Code Checks` github action
works on PRs. Basically we added `isort` to the pre-commit hooks recently, and
this does additional linting/formatting on our imports.

People reasonably have branches which were started prior to `isort` being
part of the pre-commit hooks on main. Thus, unless those branches get caught
up to main, the github action on associated PRs won't run `isort` because
it doesn't exist on those branchs. Once everyone gets their local `main`
branch updated (I suspect this might take a few days) this problem will go
away.

tests/unit/artifacts/test_base_resource.py

@@ -1,4 +1,5 @@
 from dataclasses import dataclass
+
 import pytest
 
 from dbt.artifacts.resources.base import BaseResource