Use map(str, *) in test_accessed_chunks (zarr-developers#2229)

* Update test_indexing.py

* style: pre-commit fixes

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Joe Hamman <[email protected]>

Author: 3 people

tests/v3/test_indexing.py

@@ -1782,9 +1782,7 @@ async def test_accessed_chunks(
 
         # Combine and generate the cartesian product to determine the chunks keys that
         # will be accessed
-        chunks_accessed = [
-            ".".join([str(ci) for ci in comb]) for comb in itertools.product(*chunks_per_dim)
-        ]
+        chunks_accessed = [".".join(map(str, comb)) for comb in itertools.product(*chunks_per_dim)]
 
         counts_before = store.counter.copy()