Remove redundant 'object' inheritance reference from classes (#575)

Summary:
As I understand, Captum uses Python 3, which means that classes don't need to inherit from object as it done implicitly already.

Pull Request resolved: #575

Reviewed By: vivekmig, bilalsal

Differential Revision: D25716435

Pulled By: NarineK

fbshipit-source-id: 4983e375dfc81a6c03388b009778f90b9ca34a6d

Author: ProGamerGov

captum/attr/_models/pytext.py

@@ -76,7 +76,7 @@ def get_attribution_map(self, attributions):
         return attribution_map
 
 
-class BaselineGenerator(object):
+class BaselineGenerator:
     r"""
     This is an example input baseline generator for DocNN model which uses
     word and dict features.

captum/insights/attr_vis/app.py

@@ -136,7 +136,7 @@ def __init__(
         self.additional_args = additional_args
 
 
-class AttributionVisualizer(object):
+class AttributionVisualizer:
     def __init__(
         self,
         models: Union[List[Module], Module],

captum/insights/attr_vis/attribution_calculation.py

@@ -27,7 +27,7 @@
 OutputScore = namedtuple("OutputScore", "score index label")
 
 
-class AttributionCalculation(object):
+class AttributionCalculation:
     def __init__(
         self,
         models: Sequence[Module],