Fix zarr sync

This patch removes fasteners and disables zarr.sync which uses process and thread

Author: oeway

pyproject.toml

@@ -14,7 +14,7 @@ requires-python = ">=3.9"
 dependencies = [
     'asciitree',
     'numpy>=1.21.1',
-    'fasteners',
+    'fasteners; sys_platform != "emscripten"',
     'numcodecs>=0.10.0',
 ]
 dynamic = [

zarr/sync.py

@@ -3,8 +3,6 @@
 from threading import Lock
 from typing import Protocol
 
-import fasteners
-
 
 class Synchronizer(Protocol):
     """Base class for synchronizers."""
@@ -49,6 +47,7 @@ def __init__(self, path):
         self.path = path
 
     def __getitem__(self, item):
+        import fasteners
         path = os.path.join(self.path, item)
         lock = fasteners.InterProcessLock(path)
         return lock