Auto-sized batching doesn't creates no batches when only one record

[maxf]

The _add_autosized_batches function creates no batch when only one record is passed as data.
The test below creates a single object, passes it to the function and checks that only one batch was created.
However none are created so the test fails

    @mock.patch('simple_salesforce.bulk.SFBulkType._add_batch')
    def test_add_autosized_batches_single_record(self, add_batch):
        """Test that _add_autosized_batches a single record correctly"""
        add_batch.side_effect = lambda job_id, data, operation: data
        sf_bulk_type = SFBulkType(None, None, None, None)
        data = [{'key': 'value'}]
        result = sf_bulk_type._add_autosized_batches(  # pylint: disable=protected-access
            data=data, operation="update", job="Job-1"
        )
        self.assertEqual(len(result), 1)