Add CI-related env variables to tox configuration

[AlgoFoe]

Description

What is this PR

• Bug fix
• Addition of a new feature
• Other (configuration)

Why is this PR needed?

• When running tests via tox, CI-related environment variables such as CI and GITHUB_ACTIONS are not available inside the tox environment by default.

What does this PR do?

• It adds CI and GITHUB_ACTIONS to the passenv configuration in the legacy_tox_ini section.
  As a result, these standard CI environment variables are forwarded into tox test environments.

References

• Addresses: Add CI related env variables to legacy_tox_ini #146

How has this PR been tested?

• Tests were run locally using pytest

Is this a breaking change?

• No.

Does this PR require an update to the documentation?

• No.

Checklist:

• The code has been tested locally
• Tests have been added to cover all new functionality
• The documentation has been updated to reflect any changes
• The code has been formatted with pre-commit

[IgorTatarnikov]

LGTM 🚀

Thank you!