Add second_reviewer.yml

[drew2a]

This pull request introduces a new GitHub Actions workflow titled "Second Reviewer Assignment." The primary objective of this workflow is to automate the process of assigning a second reviewer to pull requests when required, as part of our tie-breaker mechanism in code review processes.

Key Features:

1. Trigger Condition: The workflow is triggered when a label named PR: second reviewer is added to a pull request. It is designed to only respond to this specific label, ensuring that the action is executed intentionally and in the appropriate context.

2. Fetching Reviewers: The workflow fetches the list of potential reviewers from the 'reviewers' team within the 'Tribler' GitHub organization. This is done using the actions/github-script action with a custom script.

3. Reviewer Assignment Logic:

   • The script filters out the pull request author and any reviewers already assigned to the pull request, ensuring no duplicate assignments.
   • From the remaining list of eligible reviewers, one reviewer is randomly selected and assigned to the pull request.

4. Commenting on PR: After assigning the reviewer, the workflow automatically posts a comment on the pull request, explaining the selection. This comment serves to inform all participants about the automated decision and its context.

5. Handling Unavailability of Reviewers: In case all potential reviewers are already assigned, the workflow adds a comment to the pull request stating that all eligible reviewers have been exhausted. This serves as a notification for manual intervention.

6. Usage of PAT Token: A Personal Access Token (PAT) titled PAT_TOKEN_FOR_SECOND_REVIEWER_UNTIL_JAN_2025 is used due to the insufficient permissions of the default GitHub token for viewing members of the Tribler organization. This token is valid until January 2025 and will need to be replaced upon expiration.

Additional Notes:

• Token Expiration Reminder: It's important to note that the PAT_TOKEN_FOR_SECOND_REVIEWER_UNTIL_JAN_2025 will expire in January 2025. A renewal or replacement will be necessary to maintain the functionality of this workflow.

Modifications:

• Added the .github/workflows/second_reviewer_assignment.yml file implementing the workflow.

Resolves #7807

Refs:

• https://docs.github.com/en/authentication/keeping-your-account-and-data-secure/managing-your-personal-access-tokens
• https://github.com/actions/github-script
• https://octokit.github.io/rest.js/v20/