Apply ruff 0.16 and black fixes

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012U7coQfVu8nK2R4q2mCULA

tests/test_background_tasks.py

@@ -147,9 +147,7 @@ async def test_launch_waits_for_every_startup_hook_before_running_any_task():
         assert hook_call_order == ["A", "B"]
 
         handles = ds._background_tasks.tasks()
-        await asyncio.wait_for(
-            asyncio.gather(*[h.task for h in handles]), timeout=5
-        )
+        await asyncio.wait_for(asyncio.gather(*[h.task for h in handles]), timeout=5)
         # Yet by the time task-a's own body executed (after launch, which
         # only happens once every startup hook - including B's - has
         # finished), task-b was already registered.

tests/test_cli_serve_get.py

@@ -64,20 +64,20 @@ def test_serve_with_get_does_not_launch_background_tasks(tmp_path_factory):
     sentinel = plugins_dir / "sentinel.txt"
     (plugins_dir / "bg_task_for_get.py").write_text(
         textwrap.dedent(
-            """
+            f"""
         from datasette import hookimpl
 
         @hookimpl
         def startup(datasette):
             async def inner():
                 async def task(datasette):
-                    with open("{sentinel}", "w") as fp:
+                    with open("{sentinel!s}", "w") as fp:
                         fp.write("ran")
 
                 datasette.add_background_task(task, name="get-sentinel-task")
 
             return inner
-    """.format(sentinel=str(sentinel)),
+    """,
         ),
         "utf-8",
     )
@@ -96,9 +96,9 @@ def test_serve_with_get_does_not_launch_background_tasks(tmp_path_factory):
     assert result.exit_code == 0, result.output
     assert not sentinel.exists()
 
-    to_unregister = [
+    to_unregister = next(
         p for p in pm.get_plugins() if p.__name__ == "bg_task_for_get.py"
-    ][0]
+    )
     pm.unregister(to_unregister)