[Algorithm] Update discrete SAC example

[BY571]

Description

Update discrete SAC example similar to other off-policy scripts. Preparation for another PR to update the discrete SAC objective with separate actor/qvalue/alpha loss calculations.

Motivation and Context

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If it fixes an open issue, please link to the issue here.
You can use the syntax close #15213 if this solves the issue #15213

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Types of changes

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

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• I have read the CONTRIBUTION guide (required)
• My change requires a change to the documentation.
• I have updated the tests accordingly (required for a bug fix or a new feature).
• I have updated the documentation accordingly.

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/rl/1745

• 📄 Preview Python docs built from this PR

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✅ You can merge normally! (6 Unrelated Failures)

As of commit 11b8fa5 with merge base 11a82c3 ():

FLAKY - The following jobs failed but were likely due to flakiness present on trunk:

• Continuous Benchmark (PR) / CPU Pytest benchmark (gh)
  Workflow failed! Resource not accessible by integration
• Continuous Benchmark (PR) / GPU Pytest benchmark (gh)
  Workflow failed! Resource not accessible by integration
• Unit-tests on Linux CPU / tests (3.11) / linux-job (gh)
  test/test_libs.py::TestGym::test_vecenvs_env[CartPole-v1]
• Unit-tests on Linux GPU, latest stable release / tests (3.8, 11.8) / linux-job (gh)
  test/test_libs.py::TestGym::test_vecenvs_env[CartPole-v1]
• Unit-tests on Windows / unittests-gpu / windows-job (gh)
  ##[error]The operation was canceled.

BROKEN TRUNK - The following job failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• Habitat Tests on Linux / tests (3.9, 11.6) / linux-job (gh)
  test/test_libs.py::TestHabitat::test_habitat_render[False-HabitatPick-v0]

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[vmoens]

LGTM thanks for this!

[vmoens]

@BY571 I forgot: we need to adapt the examples CI too!

[vmoens]

@BY571 the examples CI is still failing because of a relative import to utils

rl/examples/discrete_sac/discrete_sac.py

Lines 25 to 33 in bfcf90a

	from utils import (
	log_metrics,
	make_collector,
	make_environment,
	make_loss_module,
	make_optimizer,
	make_replay_buffer,
	make_sac_agent,
	)