fix: s3 access #453 (#459)

## Description


Fix for issue #453 

## What problem does this change solve?
<!-- Describe if it's a bugfix, new feature, doc update, or breaking
change -->

## What issue or task does this change relate to?
<!-- link to Issue Number -->

##  Additional notes ##
<!-- Include any additional information, caveats, or considerations that
the reviewer should be aware of. -->

***As a contributor to the Anemoi framework, please ensure that your
changes include unit tests, updates to any affected dependencies and
documentation, and have been tested in a parallel setting (i.e., with
multiple GPUs). As a reviewer, you are also responsible for verifying
these aspects and requesting changes if they are not adequately
addressed. For guidelines about those please refer to
https://anemoi.readthedocs.io/en/latest/***

By opening this pull request, I affirm that all authors agree to the
[Contributor License
Agreement.](https://github.com/ecmwf/codex/blob/main/Legal/contributor_license_agreement.md)

Author: b8raoult

pyproject.toml

@@ -49,7 +49,7 @@ dynamic = [
 ]
 dependencies = [
   "anemoi-transform>=0.1.10",
-  "anemoi-utils[provenance]>=0.4.32",
+  "anemoi-utils[provenance]>=0.4.38",
   "cfunits",
   "glom",
   "jsonschema",

src/anemoi/datasets/data/stores.py

@@ -85,22 +85,20 @@ class S3Store(ReadOnlyStore):
     options using the anemoi configs.
     """
 
-    def __init__(self, url: str, region: str | None = None) -> None:
-        """Initialize the S3Store with a URL and optional region."""
-        from anemoi.utils.remote.s3 import s3_client
+    def __init__(self, url: str) -> None:
+        """Initialize the S3Store with a URL."""
 
-        _, _, self.bucket, self.key = url.split("/", 3)
-        self.s3 = s3_client(self.bucket, region=region)
+        self.url = url
 
     def __getitem__(self, key: str) -> bytes:
         """Retrieve an item from the store."""
+        from anemoi.utils.remote.s3 import get_object
+
         try:
-            response = self.s3.get_object(Bucket=self.bucket, Key=self.key + "/" + key)
-        except self.s3.exceptions.NoSuchKey:
+            return get_object(os.path.join(self.url, key))
+        except FileNotFoundError:
             raise KeyError(key)
 
-        return response["Body"].read()
-
 
 class DebugStore(ReadOnlyStore):
     """A store to debug the zarr loading."""