Fixed linting errors.

moto/core/authentication.py

@@ -122,7 +122,9 @@ class CreateAccessKeyFailure(Exception):
 class IAMRequestBase(ABC):
 
     def __init__(self, method, path, data, headers):
-        print(f"Creating {self.__class__.__name__} with method={method}, path={path}, data={data}, headers={headers}", file=sys.stderr)
+        print("Creating {class_name} with method={method}, path={path}, data={data}, headers={headers}".format(
+            class_name=self.__class__.__name__, method=method, path=path, data=data, headers=headers),
+            file=sys.stderr)
         self._method = method
         self._path = path
         self._data = data

moto/core/exceptions.py

@@ -104,4 +104,3 @@ class AuthFailureError(RESTError):
         super(AuthFailureError, self).__init__(
             'AuthFailure',
             "AWS was not able to validate the provided access credentials")
-

moto/s3/exceptions.py

@@ -219,7 +219,7 @@ class S3InvalidTokenError(S3ClientError):
     code = 400
 
     def __init__(self, *args, **kwargs):
-        super(S3InvalidTokenError, self).__init__('InvalidToken', 'The provided token is malformed or otherwise invalid.',  *args, **kwargs)
+        super(S3InvalidTokenError, self).__init__('InvalidToken', 'The provided token is malformed or otherwise invalid.', *args, **kwargs)
 
 
 class BucketInvalidTokenError(BucketError):