Apply ruff rule RUF029

RUF029 Function is declared `async`, but doesn't `await` or use `async` features.

tests/v3/test_group.py

@@ -368,7 +368,7 @@ async def test_asyncgroup_update_attributes(
 
 @pytest.mark.parametrize("store", ("local", "memory"), indirect=["store"])
 @pytest.mark.parametrize("zarr_format", (2, 3))
-async def test_group_init(store: LocalStore | MemoryStore, zarr_format: ZarrFormat) -> None:
+def test_group_init(store: LocalStore | MemoryStore, zarr_format: ZarrFormat) -> None:
     agroup = sync(AsyncGroup.create(store=store, zarr_format=zarr_format))
     group = Group(agroup)
     assert group._async_group == agroup

tests/v3/test_sync.py

@@ -1,5 +1,4 @@
 import asyncio
-import time
 from collections.abc import AsyncGenerator
 from unittest.mock import AsyncMock, patch
 
@@ -48,7 +47,7 @@ def test_sync_timeout() -> None:
     duration = 0.002
 
     async def foo() -> None:
-        time.sleep(duration)
+        await asyncio.sleep(duration)
 
     with pytest.raises(asyncio.TimeoutError):
         sync(foo(), timeout=duration / 2)