try to fix sphinx build

pennylane/data/base/attribute.py

@@ -47,8 +47,6 @@ class AttributeInfo(MutableMapping):
     attribute. Is stored in the HDF5 object's ``attrs`` dict.
 
     Attributes:
-        attrs_namespace: Keys for this class's attributes will
-            be prefixed with this string in ``attrs_bind``.
         attrs_bind: The HDF5 attrs dict that this instance is bound to,
             or any mutable mapping
         py_type: Type annotation for this attribute

pennylane/data/base/dataset.py

@@ -119,13 +119,12 @@ class Dataset(MapperMixin, _DatasetTransform):
         fields: A mapping of attribute names to their ``Attribute`` information. Note that
             this contains attributes declared on the class, not attributes added to
             an instance. Use ``attrs`` to view all attributes on an instance.
-        bind: The HDF5 group that contains this dataset's attributes
     """
 
     __data_name__: ClassVar[str]
     __identifiers__: ClassVar[Tuple[str, ...]]
 
-    fields: ClassVar[typing.Mapping[str, Field]] = MappingProxyType({})
+    fields: ClassVar[typing.Mapping[str, Field]]
 
     bind_: Optional[HDF5Group] = _init_arg(default=None, alias="bind", kw_only=False)
     data_name_: Optional[str] = _init_arg(default=None, alias="data_name")
@@ -406,6 +405,9 @@ def __dir__(self):
     from other datasets."""
 
 
+Dataset.fields = MappingProxyType({})
+
+
 class _DatasetAttributeType(DatasetAttribute[HDF5Group, Dataset, Dataset]):
     """Attribute type for loading and saving datasets as attributes of
     datasets, or elements of collection types."""