(fix): ensure zip directory store compares key to prefix correctly

Author: ilan-gold

src/zarr/storage/_zip.py

@@ -271,7 +271,7 @@ async def list_dir(self, prefix: str) -> AsyncIterator[str]:
                     yield key
         else:
             for key in keys:
-                if key.startswith(prefix + "/") and key != prefix:
+                if key.startswith(prefix + "/") and key.strip("/") != prefix:
                     k = key.removeprefix(prefix + "/").split("/")[0]
                     if k not in seen:
                         seen.add(k)