* Cache result of FSStore._fsspec_installed

Prevent runtime-overhead in doing this check multiple times

Author: ph03

zarr/storage.py

@@ -28,6 +28,7 @@
 import zipfile
 from collections import OrderedDict
 from collections.abc import MutableMapping
+from functools import cache
 from os import scandir
 from pickle import PicklingError
 from threading import Lock, RLock
@@ -1540,6 +1541,7 @@ def clear(self):
         self.map.clear()
 
     @classmethod
+    @cache
     def _fsspec_installed(cls):
         """Returns true if fsspec is installed"""
         import importlib.util