GroupBy KeyError for int type of column label

[anmyachev]

System information

• OS Platform and Distribution (e.g., Linux Ubuntu 16.04): Windows 10
• Modin version (modin.__version__): 0.8.2.1
• Python version: 3.7.8
• Code we can use to reproduce:

import modin.pandas as pd
import numpy as np
df = pd.DataFrame(np.random.randint(0, 100, size=(100, 1000)))
print(df.groupby(1).mean())

Describe the problem

Pandas works well in the case.

Source code / logs

ray::deploy_ray_func() (pid=31188, ip=10.249.225.12)
  File "python\ray\_raylet.pyx", line 477, in ray._raylet.execute_task
  File "python\ray\_raylet.pyx", line 481, in ray._raylet.execute_task
  File "python\ray\_raylet.pyx", line 482, in ray._raylet.execute_task
  File "modin\engines\ray\pandas_on_ray\frame\axis_partition.py", line 105, in deploy_ray_func
    result = func(*args)
  File "modin\engines\base\frame\axis_partition.py", line 223, in deploy_axis_func  
    result = func(dataframe, **kwargs)
  File "modin\engines\base\frame\data.py", line 1034, in _map_reduce_func
    series_result = func(df, *args, **kwargs)
  File "modin\backends\pandas\query_compiler.py", line 2635, in <lambda>
    axis, lambda df: groupby_agg_builder(df)
  File "modin\backends\pandas\query_compiler.py", line 2632, in groupby_agg_builder 
    return compute_groupby(df.copy())
  File "modin\backends\pandas\query_compiler.py", line 2609, in compute_groupby     
    grouped_df = df.groupby(by=by, axis=axis, **groupby_kwargs)
  File "miniconda3\envs\modin\lib\site-packages\pandas\core\frame.py", line 6525, in groupby
    dropna=dropna,
  File "miniconda3\envs\modin\lib\site-packages\pandas\core\groupby\groupby.py", line 533, in __init__
    dropna=self.dropna,
  File "miniconda3\envs\modin\lib\site-packages\pandas\core\groupby\grouper.py", line 786, in get_grouper       
    raise KeyError(gpr)
KeyError: 1