Sort scheduler regression test imports

Fix the import ordering in the new scheduler regression test module so
isort and the nox CI session pass.

Signed-off-by: Mathias L. Baumann <mathias.baumann@frequenz.com>

Author: Marenz

tests/test_scheduler_regressions.py

@@ -4,22 +4,21 @@
 """Regression tests for scheduler edge cases."""
 
 import asyncio
-from dataclasses import dataclass
-from dataclasses import replace
+from dataclasses import dataclass, replace
 from datetime import datetime, timedelta, timezone
 from random import randint
 from typing import Iterator
 
 import async_solipsism
 import time_machine
-from frequenz.client.common.microgrid import MicrogridId
 from frequenz.channels import Receiver
-from frequenz.dispatch import Dispatch, DispatchEvent
+from frequenz.client.common.microgrid import MicrogridId
 from frequenz.client.dispatch.recurrence import RecurrenceRule
 from frequenz.client.dispatch.test.client import FakeClient, to_create_params
 from frequenz.client.dispatch.test.generator import DispatchGenerator
 from pytest import fixture
 
+from frequenz.dispatch import Dispatch, DispatchEvent
 from frequenz.dispatch._bg_service import DispatchScheduler