(v3.1.8) Sinergym truncated flag update

[AlejandroCN7]

Description

This patch causes Sinergym to use the truncated flag instead of terminated when the episode has been completed naturally without any event causing it to be forcibly terminated. For more information, visit the referenced issue.

Motivation and Context

• [x] I have raised an issue to propose this change (required for new features and bug fixes)

Why is this change required? What problem does it solve? Please, reference issue or issues opened previously.

Fixes #384

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)
• [x] Improvement (of an existing feature)
• [ ] Others

Checklist:

• [x] I've read the CONTRIBUTION guide (required)
• [ ] My change requires a change to the documentation.
• [x] I have updated the tests.
• [ ] I have updated the documentation accordingly.
• [ ] I have reformatted the code using autopep8 second level aggressive.
• [ ] I have reformatted the code using isort.
• [ ] I have ensured cd docs && make spelling && make html pass (required if documentation has been updated.)
• [x] I have ensured pytest tests/ -vv pass. (required).
• [ ] I have ensured pytype -d import-error sinergym/ pass. (required)

Changelog:

• Adapting the truncated flag updated in Sinergym environment layer.
• Updated all examples and script to use truncated and terminated to do a reset automatically.
• Sinergym loggers (CSVLogger class and wrapper) log truncated flag in monitor.csv too.
• Updated tests.