feat: add auto PR / issue close after being stale for a certain amount of time

[monilpat]

Relates to:
#1318

This PR addresses the need to manage inactive issues and pull requests by implementing a workflow that automatically marks them as stale after a period of inactivity.

Risks

• Risk Level: Low
• Potential Impact: The workflow may inadvertently mark active issues or pull requests as stale if there is a lack of recent activity, potentially causing confusion among contributors.

Background

What does this PR do?

This PR introduces a GitHub Actions workflow that automatically marks issues and pull requests as stale after a specified period of inactivity and subsequently closes them if no further activity occurs.

What kind of change is this?

• Features (non-breaking change which adds functionality)

Documentation changes needed?

• My changes require a change to the project documentation.
• I have updated the documentation accordingly to include information about the new workflow and how it manages stale issues and pull requests.

Testing

Where should a reviewer start?

Review the newly added workflow file located at .github/workflows/stale.yml.

Detailed testing steps

1. Review Workflow Configuration:

   • Ensure that the days-before-stale and days-before-close parameters are set to appropriate values that align with the project's maintenance policies.

2. Simulate Inactivity:

   • Create a test issue and a test pull request.
   • Manually adjust their timestamps to simulate inactivity beyond the days-before-stale threshold.

3. Trigger Workflow:

   • Manually trigger the workflow to process the test issue and pull request.
   • Verify that the workflow adds the 'stale' label and posts the configured stale message.

4. Simulate Further Inactivity:

   • Allow the test issue and pull request to remain inactive beyond the days-before-close threshold.

5. Trigger Workflow Again:

   • Manually trigger the workflow again.
   • Verify that the workflow closes the test issue and pull request and posts the configured close message.

6. Activity Check:

   • Create another test issue and add a comment before it reaches the days-before-stale threshold.
   • Ensure that the workflow does not mark it as stale, confirming that activity resets the inactivity timer.

Discord username

0x8664