feat(cinder): Add get attachments tool(#70)

- Add get attachments tool
- Tests are updated and passing

Author: S0okJu

src/openstack_mcp_server/tools/block_storage_tools.py

@@ -236,6 +236,8 @@ def get_attachments(
         """
         Get the list of attachments.
 
+        :param volume_id: The ID of the volume.
+        :param instance: The ID of the instance.
         :return: A list of Attachment objects.
         """
         conn = get_openstack_conn()