Bugfix/ppo mask stats window size

[PatrickHelm]

Description

I made the changes proposed in #198

Context

closes #198

• I have raised an issue to propose this change (required)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (update in the documentation)

Checklist:

• I've read the CONTRIBUTION guide (required)
• The functionality/performance matches that of the source (required for new training algorithms or training-related features).
• I have updated the tests accordingly (required for a bug fix or a new feature).
• I have included an example of using the feature (required for new features).
• I have included baseline results (required for new training algorithms or training-related features).
• I have updated the documentation accordingly.
• I have updated the changelog accordingly (required).
• I have reformatted the code using make format (required)
• I have checked the codestyle using make check-codestyle and make lint (required)
• I have ensured make pytest and make type both pass. (required)

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[araffin]

Thanks, please update the tests too =)

[PatrickHelm]

Could you please specify what you mean by "update the tests"?
Should I add a test to confirm that the change is correct or modify the existing tests somehow?

[araffin]

Should I add a test to confirm that the change is correct or modify the existing tests somehow?

yes, test is there:

stable-baselines3-contrib/tests/test_run.py

Lines 153 to 161 in 35f0625

	@pytest.mark.parametrize("algo", [TRPO, QRDQN])
	@pytest.mark.parametrize("stats_window_size", [1, 42])
	def test_ep_buffers_stats_window_size(algo, stats_window_size):
	"""Set stats_window_size for logging to non-default value and check if
	ep_info_buffer and ep_success_buffer are initialized to the correct length"""
	model = algo("MlpPolicy", "CartPole-v1", stats_window_size=stats_window_size)
	model.learn(total_timesteps=10)
	assert model.ep_info_buffer.maxlen == stats_window_size
	assert model.ep_success_buffer.maxlen == stats_window_size

[PatrickHelm]

Thank you for your hint. I updated the test as well.

[araffin]

LGTM, thanks =)